Just got a '87 mustang(2.3)...

its cheaper to invest into a 2.3 turbo motor over a 5liter. Not much in power builders for na 2.3's.

the front clip should fit with out a problem

It should be easy to swap front clips. The only bumps in the road I see are the need to get headlight wiring for 4 lamps vice 2. I have not done this swap, but I have an 82 and an 89.

Unless you just want to tinker with the N/A four, I would think a turbo or 5.0 is a much easier way to go fast.

I just happen to really have a soft spot for the 2.3 engine, and would like sometime to have a strong one.