I think that a 3.1 or 3100 will work for you, but if you can find a 3400, you should snag it! If it's out of a junked car, make sure to grab all the comp. stuff as well, as it will help with the whole bolt in effect.
As for a V8 in it, with a little imagination, you could fit almost any engine in almost any car. I once saw a guy who had a 454 in a 1960's VW Beetle!