340clone - I would check the stall speed with your current package. Engine fully warmed up, bury your foot on the brake pedal and raise the engine speed until the tires break loose. Shouldn't take more than 2 or 3 seconds to get to the max engine speed.

Do that once, run in neutral for 30 seconds place in drive and do it again. Average your two results and that should get you a fairly accurate stall speed. If by chance you have a manual shift auto place it in third and do the test.

For a few hundred RPM potential change sounds like you may be better off leaving things alone.

You have a known quantity with this converter.
Starting with a new converter opens you up to all kinds of potential issues.

The other thing many people don't understand is that STR differs between converters.
They all look alike from the outside.