what torque converter

10" Turbo Action 17805s medium, or even the standard loose version from Bob Mazzolini, $529 shipped, (as listed on his eBay listings). I'll venture to say that your specs are pretty common like most of our builds are vs really unique and therefor maybe requiring a high dollar overkill specd true custom build. Save that stuff for full time race setups. You call one of those builders you'll likely be looking at a $900 9.5" 3800+/- stall, 4200+/- flash stall converter. Stick with the better known off the shelf brands. You'll do just fine.