upgrades for 42RH during rebuild???

[str12-340]

I recently purchased a 42RH (A500) for my Dart street car. I'm going to get it rebuilt and was wondering what upgrades folks had made during a rebuild that worked out well for them. I am mostly concerned about reliability and durability. It will be behind a 350hp small block. All suggestions appreciated - specific sources and part numbers would be welcomed!!!

 

[CudaFactHackJob]

Most direct drums in these only have three clutches. Change drums to one with a higher snap ring groove or use a forward clutch ridged bottom plate on top. Also, use Red Eagle thins .061 to stack five in there. You have to twist the waved retaining ring back and forth to get it in but it will go. Oops, I thought you said 518... The ridged bottom plate will sometimes interfere with the forward drum.