2.25 petrol

hi
I have just go a 1987 90 petrol after a bit of of checking I fine that if has had a engine change to a 2.25 petrol but still got the 5 speed gearbox from the 2.5 will this make a difference to it .
It also burns a lot of oil as well as petrol about 10 mpg not good and very slow so I was going to rebuild the lump new rings and shells. Was thinking of fitting a stage 2 head with a gas flowed manifold will this help at the moment the compression is down to about 50 BHP any help please

I would look for a decent secondhand 2.5 petrol and fit that.
The 2.25 is underpowered, imo, for a 90 with perm 4wd.

Sounds like the motor is getting worn. The 2.5 petrol should be straightforward swap and will give you some extra power about on par with the 19J diesel. One approach would be to buy a 2.5 and overhaul it, then fit the rebuilt unit to your 90. You should see an improvement in fuel consumption as the more powerful engine won't be working so hard all the time. Alternatively there's the 200/300tdi which give better power and fuel economy but will need more work to fit.

As above, a decent 2.25 petrol has about the same power as a decent 2.5d, but the 2.5 does about 30mpg. You'll struggle to get 20mpg from a petrol unit, even with electronic ignition, flowed head, uprated plugs and leads, low friction additives etc - I tried.

You'll always find someone who'll buy an old complete and still running 2.25.