67 cuda FB progress UPDATE

I don't know what to do..
Should I rebuild the numbers matching 273? Or purchase a 318 and build that as a replacement? I'm fuguring the cost to build the 273 up again will set me back close to $3,800 and to build a 318 is about the same. thing is, I can get more from a 318 at that cost. BUT the numbers matching 273 is my dilema. The 727 trans is also the origional for this car. Would I be better off in the long run with going with what came with the car from the factory? My son want's to put a 360 in. Figures!!
I would too if I was 16 again. Any suggestions or ideas are greatly apreciated. Thanks guys...