Reply to "UK GT5 Full engine rebuild - 351 Cleveland aiming for 400bhp"

FWIW:

I think you mentioned it somewhere earlier, but it would be a good time to upgrade the clutch. My personal experience (and several friend's experience with 500hp cars, non-pantera but various small block Fords) has been, that at ~500HP single disc clutches quickly become wear items. Of course it depends a lot on the driving style as well. It's not that difficult to wear out single disc clutch in one summer.

After several years of experimenting with different manufacturers and friction materials all of us have ended up with twin disc clutches (mostly McLeod I think), and haven't had to change clutches since. It is heat that kills the clutch and twins have double the surface to get rid of it and double the amount of material to wear. They may rattle though if idle is low and the cam is lumpy.

Single discs we have worn out so far include at least several Centerforces, RAM, Anderson hi rev, Hays, Motorsports, Spec Kevlar (that went very quick behind 550hp Windsor). It's not to say they don't work, just wear out fast.
Edit: All 10.5" except one 11" centerforce that didn't last any longer. All diaphragm, except one RAM that didn't last any longer.