Hmmmmm. As most of you know I sold my roadster and used the money to buy an XJR. This kind of got me thinking. The Jag V8 engine is actually very light, as is the Merc 5 speed auto trans (yes, I know, but bear with me). My car has been lightly tuned to about 420 BHP, in the very big Jag it does the 0-60 dash in 5 seconds and storms the 0-100 in about 11. Top speed when derestricted is 180. I am told it is a fairly simple matter to up it to about 500 brake.
Now, I don't know if that engine would fit or whether it could be mated to a manual box but I wouldn't mind trying
You can get a decent Jag v8 engine for about 350, an auto box would be about the same albeit totally useless for a roadster.
Failing that the Honda would seem like a great choice.
Dave.