I think my 727 is fried. Now I'm at a crossroads...

With a 4spd you don't get the same torque multiplication of an automatic's converter. So that can be addressed with cam and/or gearing(trans and/or rear axle) changes.
I think a big difference between the two options would be the carburetor and the distributor advance curve.
Of course, the previously mentioned pilot bushing situation will need to be addressed if you want to go with the manual trans.