Larry,
A couple things determin the stall speed. Converter size; 12"-stock, 11" street performance, 10"- street strip, 8 or 9" race converers. Take a 11" street performance converter, the vanes inside can be angled slightly different so that it is rated at 2400 to 2800 rpm. That doesn't mean it will stall at that point , engine torque and vehicle weight determine where that converter will stall. A light car 2,200 lbs will not stall as high as a 2,800 lb car,you don't load the converter as much. The other big factor is low end torque. My big block makes over 500 ft/lbs of torque right at 3,000 rpm,thats where my coverter stalls. Put that same converter behind a stock smogger 220 hp big block and the torque is 360 ft/lbs and will stall about 2,500 rpm. Your 347 should make decent power at 2,500 rpm but not huge torque numbers, so you could go with a 11" street converter rated at 2,400 to 2,600 rpm and still lock up at freeway speeds, just run a good B&M 18,000 lb trans cooler. I have no problem with my trans temperatures.
Good Luck,
Perry.
