[PJS50]

I am pumping 600+ HP and 645 or so Ft-Lbs of torque into an 8.8" unit...
No problems yet (knocking on wood)... I know of somebody pushing 720+ HP into an 8.8" unit in his SPF and he isn't experiencing any problems either... You have to remember that our cars are so light, that the "rated" HP/Torque on those rear ends doesn't usually apply because they were "rated" for a 4000lb Thunderbird Supercoupe...
There are custom made 9" Ford based "independent" units available out there that can take way more then I am dishing out that would STILL be less $$$ then an "original" NIB condition Salisbury type... I know Everett Morrison was offering the Ford 9" Ind. rear end as an option before they changed to their current roller configuration (maybe they still do?)... Contact them to see where they were getting them from...
I seem to remember that unit running @ $3500 from EM? That was a few years back though and the memory ain't as good as it used to be...
How many HP are you developing with your FE?
Elvis has left the building...