Diesel or Petrol

Syncro on 2nd on a Ser II? Where did you find that?

Back to the original question, I would go for petrol. If you have got it to tinker with, there is more you can do, and it will make sense if you are used to bikes. From what you are saying about use, fuel consumption will not be critical. For 2 1/4 petrol you should expect 15 mpg, but correctly tuned and carefully driven20 is possible, over 20 and you are being very lucky.

V8s may sound nice but think carefully about any none standard engine. Even if it is a well done conversion can be a nightmare for something as simple as replacing the top hose, unless it came with a list of all parts used in the conversion (very unlikely.) If it's not been done well......

teflons back on top form today ,

just looked at theat SII 88" Derv..... hope you didn't pay £2,130 for it!
That's a lot of money for something that I'm sceptical Is an 'original SII Diesel'... there's no photo of the red 'Land-Rover Diesel' badge they had, while mention of the engine having a different number to the VIN tells that it ISN'T the original engine.
Otherwise, what you have is a 'worthy' little SII in 'useful' but essentially unrestored condition (that without the original engine, ISN'T worth that sort of money, or NOT restoring properly), worth about £1200ish.
At that kind of money, (maybe a tad more, perhaps 15/16 if you REALLY wanted it), it would make a great weekender, you could tidy up and fettle the way you wanted it as you went along, though it would probably need chassis patching from time to time and at some point, you'd probably be looking to re-chassis it and do a full 'ground-up'.
Keep looking, there are plenty out there.