Put the rebuilt 318 in it and wait until later. I have been collecting NOS parts for my Barracuda one at a time as they show up with a decent price. You can do the same with your engine so it isn't such a big bite at once.
I forgot to mention that the rebuilt 318 is in it..whoops. Just looking for some cheap bang for the buck with what I have. I am kind of attached to the little motor because it was hard to spend what I did on it at the time. Silly I know...
You are probably on to something with that though. I could just take and build a 360 a little at a time. The 360 would probably stay with the car forever.