Performance torque converter for 64 Pushbutton 904

I'm trying to find a slightly higher stall torque converter for my 273 Commando powered Barracuda. This is a 64 with pushbutton trans with the 18 spline input shaft. The transmission is already rebuilt and ready to go and I don't want to tear it down to replace the input shaft with a later model fine spline one. Where can I get a nice street converter with maybe 2000 stall?