dont look for the easy way out, all conversions require very similar mods & upgrades.
if you do end up doing a conversion, your going to gain a heap of knowlege about the mechanicals you decide to use
so you'll be an expert in no time

your engine choice should come down to what you want from the car, what you plan to do with it
and if you plan to drive it on the street make sure you can get it legally registered (engineered)

good luck