The two stroke triple is quite short, especially being 3 quite small pots under 300cc and no need for any valve timing mechanism at either end of the engine, hence the original 96 having the "bullnose" front and the rad being mounted behind the engine.
The 2.3 and 2.8 Cologne V6s will go straight in, fix to the same engine mounts and the bellhousing pattern is identical. However, they are too long and you need to relocate the rad.
We used to have an ex-grass track 96 that had been run with a V6 for a while, but the extra weight ahead of the front wheels meant it handled like a dog, so a hottish V4 was fitted instead (hence why we got it). The rad was where the back seat used to be in typical autograss style. Was good fun razzing it round the field behind our house when I was a kid
There is a chap in the UK with a V6 in a road car, but has had to mount a big rad above the engine towards the rear of the engine bay with twin fans, replacing the heater gubbins - not seen it for a few years, and not sure how cool it stayed...pics:
and a twin turbo V6 in Finland:
No idea what this guy has doen to cool it though!
(pics via Alec Dearden's
V4 website )
So the short answer is - yes it's do-able, but a bit of a faff and you then REALLY need to sort the handling out.
There's a chap in Leeds putting a C900 8v lump into a 95 shell, he reckons the weight being right over the box will actually improve the weight distribution over a standard V4.