I'll be a dousche and say it doesn't matter, it will never run, just cause I can
<3 you matt, no homo

...but, to stay on topic, ls based would be neat, as would an f20c, or maybe a ca18det? Worlds of motors comes to mind for that chassis, seeing as I wouldn't mind owning one, but I would stay volvo, have fun with that, then throw something else in.