My personal extensive experience is that the starters coming from O'Reilly and Autozone for FE motors are complete garbage. The snouts break, the bendix ceases to acctuate, the motor doesn't turn. It's one thing after another with them. I no longer buy starters from those companies. Instead, get a good rebuildable core and have a local automotive battery and electric shop rebuild the starter. Once I started doing that, no more starter problems.
I have them rebuilt by our local NAPA or buy one of their reman starters.......and you can add Advance Auto starters onto that list......
I'm thinking its the starters themselves because I have the same stock setup and haven't had any problem with hot starts........