you are looking at doing a HALF fill then if your going to drive it at all. they stabilize the cyl wall from flexing out in the middle, and the coolant that stays in the block is at the top of the cyls, so they still cool ok. you may have to go with a bigger rad just for capacity if not the core, but you'd be surprised how manageable it is.

i don't know much about ford motors-someone should chime in with advice to whether you even need to be doing this at your power level. do you have plans to beat on the motor with more power-that might help you decide