Hi Perro
Must be nice to have that sort of money to spend, so you should be able to take your pick. I could only afford a 1986 4/4 with the 1.6 xr3 engine and 5 speed box. I regularly drive mine to work (140 mile round trip)using the M50 and M5, and keep at about 80mph whenever possible. It likes this as a cruising speed. I do go to 90mph, but it becomes a little strained at this speed. Still, there isn't that much that comes past me ! However, if I had the choice, I would go for the bigger engine for more fun on the twisty bits !
Let us know how your testing gets on.
Matthew