I have a Performance Automotive Warehouse catalog (2005) that list a rebuild kits for 429 - 460 from $851 to $1048.
kit includes: crank, rods, pistons, rings, bearings, cam, lifters,
oil pump, timing chain and gear.
I have heard that the 429/460 is the cheapest Ford motor to rebuild.
Now I would not want a lot of the parts in the kit, but you could build a mild motor with a butt load of torque for a very little money.
At one horse per cubic, you would have 460 hp.
600 hp from a 460 would be easy.
Great motor.
Dwight