Frank,
I think $5500.00 is a little steep for a 351 and 5spd. you are going to have to rebuild. What Tremac tranny are you considering? If it is the 3550 with a 351, the driveshaft won't be long enuff to get into phase, they tend to bind up when using the 8.8 Mustang or T-Bird rearends. The solution is to go with the T-Bird IRS, which is rigidly mounted, no probs with angularity movements there. There are a ton of engine builders offering 351 packages, not just the FMS options. Go here,
www.cobraforum.com
FFR's 24/7, no opposing views welcome, be one of the family.
Later,
Greg