Stroller,
There are several reasons why I prefer the Type-R engine:
It's 197BHP and normally aspirated, so it will have plenty of poke (more than any standard k-series engine offers), and throttle response is good (I've driven an S2000 on road & track, and a Civic on the road), which can only help adjustability.
The next thing for me is that I want reliability, and I'm not convinced by the Rover options. Everyone I've known with a car fitted with a k-series engine (214, elise, freelander, caterham) has had head gasket issues, and other niggling faults. The t-series could be a laugh because of the potential offered by a turbo, but from my brief scan of the market, getting a relatively fresh engine looks difficult, and although I've not read of many problems with this lump, I suspect the Honda engine / box combo, certainly the 'box, is a safer bet. Furthermore, getting hold of a newish (sub 20k) Type-R engine is pretty easy.
Finally, the sound of a vetec engine at 8000 rpm is great, and I believe would suit a 5EXI brilliantly.
I suspect there's a slight premium to pay for a type-r engine (~£2k), but it's something I'm quite happy to absorb for the above.
Have you read the WKC build articles? Nothing in it has scared me off, and I'm just an office monkey with some car fettling experience - in the middle of an 1.8t transplant into a mk2 golf, clutch changes, helping mates with engine / gearbox changes, and soft rod modifications. The hardest parts to me looks to be the wiring and bodywork - I suspect there's scope for expensive errors when cutting holes in the GRP bodywork!
Good luck with your kit car decisions.
Limpabit - what tools have you bought during the build? Asides from the wiring, what aspects of the build have you found the most testing?
cheers
John.