Because the way that tight converter loads the engine. You want the convethere rter to flash above your lowest cruise RPM. I’m betting whoever it was sold you a converter with an 11 inch case. I would think a 10 inch case would be the biggest and probably a 9.5 inch case would have been better. It may have only went 3000-3200 but that’s a grand above what you have.
Those tight converters load the engine harder at lower RPM, changes the timing curve you can run and affects how the engine makes RPM.
All driveablity factors.
