In your opinion a 4.0 ltr rover v8 is a good basis for such a car?
So, IMO and without wanting to derail Nicks thread,
No.
I'm not fitting a SBF to mine but the Rover V8 was one I looked at and dismissed early on.
Firstly it's really under powered. As
@IanAnderson says, £10k for ~250hp. There are plenty of other (massively) cheaper engines that will give that "out of the box". I mean for real cheap you could do worse than just drop in an Audi V8 complete with matching gearbox.
The stock SBF 289/302 was rated for about 200-230hp so if you're not too bothered about power then just dropping a stock one in will give you almost the same power for less cost. With relatively little work you'll see 300hp+ and 400hp is achievable reasonably easily for less than you'd spend getting a mere 250hp out of the RV8. Hell for £5k you can pick up a blueprinted "Crate" long block SBF from Real Steel with 330hp. Another £k or so on ancillaries and it'll do that 330hp all week long.
Secondly,
beware the path less travelled. It's all very well and good thinking "oh I can do this and it'll cost less" but in the long run its cheaper and easier to do what everyone else has because they have already run into all the problems. Yes people have fitted the RV8 into GT40 replicas but that was really when SBF's weren't available here and they've typically used the UN1 (which are getting a bit rare now) and using a different box to the one the chassis has been designed for brings all new problems. I've run into a whole load of problems (and additional cost) that
I have created for myself. While I don't regret not going SBF, in hindsight if I was to do over I would.
Finally, while I would never suggest someone "build for resale value" as every build is personal what Ian said is also true, a GT40 with a different engine will be worth less. It can be worth it to you if you want something particularly special or different but in honesty the RV8 is not that special. It's only advantage is that it's light and highly available in the UK. It's not
that light though, about 230Kg fully loaded and not that small either. A 1UZ for comparison (with all ancillaries) is 215Kg, smaller and makes 260-300hp (depending on year) without any modifications. You could well end up out of pockets both ways, costing you more fitting the RV8 to get the same power *and* then also losing more money when you finally come to sell it
Of course the other side of the coin is if you already have a 300hp RV8 sitting around doing nothing then while not ideal it is probably going to be worth it because that's something you don't have to spend on that can be spent elsewhere.