try here!
Have you tried
www.enterpriseengine.com??
Columbus Ohio.
They specialize in 5. 9 rebuilds and HEAVY MODS, among other things.
Ask for Doug.
They also have good sources for Brownie boxs, and Allisons.
And, if you need the old girl resprung, there is an excellent spring shop down the street from them. I drive 4 hours to get work done down there.
You can get 300 out of the old engines, but it takes some pricey injectors and a turbo change, and some pump work.
My Dad has a 87 Ford Cabriolet w/sleeper/ dually trailer toter, that was converted from Ford 460 to a 1992 5. 9, Allison, and a Brownie. 180 hp stock runs good, but is sleepy. It weighs 9000 empty.
But you have the gears to off set that.
They started with Allison only w/ 3:73 gears. Then added the Brownie with 4:10s.
I think 300hp would be much better!!!