I suppose a downside of doing that is that strictly speaking you could fall foul of the DVLA rules on rebuilt vehicles retaining their identity, because your chassis would no longer be standard spec.
Absolutely; rules state direct like-for like replacement,
un-modified chassis.
Hack one about, whether you get the maker to do it, or whether you DIY, you would NOT have a qualifying chassis, and by the letter of the rules, SVA would deem it not the originally registered vehicle, demand a Q-plate and loss of Historic Vehicle Status
Presumably you could just weld a complete X-member 3" further foreward, and hang the rad support brakets on the back of it. Fit an apron, and nobody will ever know.
Err.... yeah..... you know that tax evasion is a rather seriouse crime, dont you?
Practically........
Giving the idea a miss would be a good one, series sterring if properly sorted is very nice, and even with wide tyres shouldnt NEED power assistance.
But there are ways and means and some ways are better than others, so have a long hard thing about it before considering the options, and the SVA & HVS implications.
Using a coiler PAS box is not a great idea the whole steering linkage is different.
On a coiler PAS box sits on the inside of the drivers side chassis rail, about where the cross member is on a series chassis, with a jointed shaft running to the steering wheel through the bulkhead, and a long drop arm working the shorter radius arm on the nearside swivil directly.
On a series the steering box is on a leg off the outside of the chassis, with a long shaft coming straght out of the box to the steering wheel, a drop arm working vertically acting on a drag link to a relay in the front cross member.
Now, the series and coiler axles are different widths; so, if you mounted coiler PAS box as on a series chassis rail, first the coiler drag link would be too long, and the series drag link too short.
You would have to put the PAS box where the relay would be in the front X-member and use the series drag link.... HOWEVER, you'd then have the problem that the run of the steering column would br rather awklward and not doable with stock parts, while the lever ratio's between PAS box drop arm and series akkerman arm would be rather too high.
You could try and mount coiler PAS box on series steering box bracket, and use an abreviated steering column off the input shaft, with the drop arm working vertically, as that's length is closer to that on the end of the series box, and it would much more closely mimick the series set-up, but i dont know how the coiler PAS box would like being turned through 90 degrees wrt the oil levels and the like!
Scratching it; if you google Terri-ann Wakeman's site, she has a nice example of a PAS conversion using an international Harvester steering box, and a defender steering column, which is the model for many suggested PAS conversions, using plant steering boxes.
Last two alternatives are the 'electric' steering column idea mentioned on here before, using bits salvaged from a scrap hatch-back or one of the proprietry kits of e-bay....
Suggestion is that they can be fitted up to the existing steering column shaft leaving everything else as is. But while it looks a nice idea, some number crunching also suggests that they dont have the 'grunt' to do anything very useful.
Other notion is Chris Perfect a few years ago offered a horendousely expensive, but quite useful auxilliary ram, PAS system, that was a complet ebolt on kit, leaving the series steering essentially standard, fitting a hydraulic ram to give assistance where a steering damper might be added.
Good, simple, expensive, and no longer available... though you might chase one down second hand on e-bay or something, and Paul Haystee in holland might stil be able to supply them new, or at least the components, if you ask him nicely.
HOWEVER..... the CAUTION I would seriousely advice is this:-
IF you modify the steering IN ANY WAY..... go SVA.
I think that you loose one point for non original steering by the ident rules point system, which oin its own isn't enough to loose historic vehicles status or demand re-registration.
BUT it IS a 'Safety Critical System', and no matter how much common sense, reasoned argument or good workmanship we apply, SVA is the ultimane buck-stopper, should there be any question over the vehicle integrity when modded.
Its an assurance that would answer a loty of silly questions by insurance companies; and heaven forbid we should ever have to, but IF unlucky enough, silly Q's by plod of lawyers!
And with a Tax Exampt Landy; Even if you restore it ABSO-BLUDY-LUTELY standard, with all the finger pointing at Tax Exempt landies and the challenges to thier HVS made on teh forums, sticking one in for SVA, with a build book, and getting a letter back on VOSA headed paper telling you THAT vehicle has been evaluated and not deemed to need SVA and they agree its still the vehicle originally registered and NOT modified sufficiently to need safety inspection HAS to be a very good insurance against the tax man, and a sales tool, if and when you come to sell it on..... basically you can give the buyer catagoric assurance of what they are getting and that its fully legit.
Sorry to be harping on, but I REALLY want to try and sell SVA as a tool we need to start looking at as our 'freind' rather than a niggling bit of red-tape hassle, and using it to our advantage, rather than trying to avoid it.
