Rebuild 904 or swap for 727?

LOL. Wow, I didn't realize I would stir up such a hornets nest. I asked the original question and read all the replies. Some of the information was above my head and some just hurt my head. This car will be a street rod and probably not get onto the track more than a couple of times and for more fun than trophy chasing.
In short, I gathered the following:
My existing 904 will fit and be strong enough to handle the 360 I will put in front of it. (so just rebuild it for piece of mind)
If I wanted to swap out to a 727, I would have to get one and possibly modify the firewall and floor??