I've got a '68 Skylark running the 350-4. Original trans ST-300 and rear end 2.56, tires are 245/60/R15 (26.5Inch). I'm curious what RPMs other's are seeing around 70mph cruising. I read around 3400. I have a suspicion this is over by around 1000 rpm. I do have failing torque converter symptoms, however the fluid level is good and doesn't seem burnt. Thanks for any help!