THOUGHTS ON THEE BEST HYDRAULIC LIFTERS FOR A STOUT .508 CAMMED 371???

The Rhodes lifters are a fast bleeding lifter that reduce duration and lift effectively reducing the cam size. Are you sure you want to go this route? (I would not.)

Hughes engines offer Johnson hi lift lifters. There fine for use and can be gotten cheaper else where. They are a good lifter but I’d check any lifter that comes to the table regardless of who’s name is on the box. Disassemble, clean and inspect, lube up, reassemble. Do not fill with oil. Just coat it with oil and wipe it clean for easy assembly.

Depending on the weight of the car, that cam will like a RPM AG, a 750 carb and a 4.10 gear on 26 inch tires.
Your converter is OK for use. It maybe a bit high, but it’s a LOT better than being to low. I’d run it.
Run a trans cooler.

Weight dependent, you have a easy 13 second car set up.