Stock convertors for 1970 were rated at 2185 rpm for most of the 400's and 2460 for the RAIV and 455's.The torque multiplication ratio was 2.04 and 2.30 respectively.

I had a switch-pitch torque convertor in my '69 that allowed me to have a stall speed of about 1500 rpm or about 2800 rpm. When driving around "normally" I preferred the feel of the low stall but when I wanted to make tracks, high stall definitely helped!

Under full throttle, the higher the stall the harder the car will leave the line. Under light throttle the engine will rev higher to produce the same acceleration as a low stall convertor and will "feel" sluggish.

If you have a high stall lock-up convertor you're getting the best of both worlds already.