What rpm stall converter should use?

A somewhat easy to understand explanation of things: https://www.svtperformance.com/threads/torque-converter-stall-torque-ratio-str-guide.1113661/

After reading that, yikes, yeah, I’d just call one of the companies others here have mentioned (including Turbo Action and FTI) and get the right converter the first time. There are a couple you could run “out of the catalog” and be happy with, but for the amount of money you’ve paying regardless it’s best to let the pros spec “the ideal one”