302 and 351 are badass street engines.

Not something to f*ck with.

 

No offense intended, but people who really know what goes into building a 9 or 10 second car generally don't have to ask what kind of engine to use or say things like "What's a 5.4L?"

Especially since your question doesn't have an answer. "Best" is a relative term. It can mean "cheapest" it can mean "easiest" it can me "coolest" it can mean any number of things.

What kind of engines have you used in your previous "9 or 10 second cars"? What are you trying to build other than a car that does the quarter mile in 9 or 10 seconds? Streetable? Bare bones? Trailer queen?

What you've essentially asked is "what kind of car should I get"... and no one can really answer that question for you as everyone will have an opinion and many of those opinions will be accurate and won't necessarily be what YOU want.