You could put regular 360 or 390 heads on it. They will flow MUCH better than the heads you have now. Problem is, you have to replace the intake too, since the FT intake wont match up to the FE heads. Also, you'll need to use an FE distributor and get a bushing for the block, since the FE distributor is smaller than the FT one. You can get one at DSC
and they call it the "Ford Truck Block Distributor Bushing." It's about 3/4 of the way down the page.
You dont want 390 pistons. Most of them are the truck variety and have a 1.680" compression height. This will lower compression back down, and make a gutless wonder. FWIW, some 390 car pistons have the correct 1.776" compression height, and are the same part as 360 pistons. Just tell 'em you want 360 pistons and you cant go wrong.
Cam gear might be a problem. The FT has a bigger crank snout than the FE, so that prevents you from using the aftermarket pieces available. What I would do, is get a replacement FT timing set and use the aftermarket cam with it. Should work good.
If you decide to do a head swap and use FE heads, your compression will go up since you will have less combustion chamber space. In this case, use the Crane 343941 cam. Then you'll have a real runner. The difference will be night and day.