If the carb is fully wide-open when the gas pedal is floored, at least you know the throttle cable is adjusted properly. So check that with the tranny cable disconnected. Adjust as necessary, and don't touch the throttle cable again. Now attach the tranny cable. At wide-open with the gas pedal floored, if the lever on the transmission is 99% all the way back (basically against the stop) you have the tranny cable adjusted approximately right too. But if the tranny cable is now stopping the carb from going wide open, then you have no choice but to put a little more slack in the tranny cable. Work in 1/16" adjustment increments until that tranny cable does what it's supposed to do. Even if it only pulls the lever back 90% of the way, you should be able to drive the car. Adjusted this way, the car should be drivable, and probably will be shifting good. If it isn't working you must have something else wrong. I am no tranny expert, but the next thing I'd check is to see if the fluid is getting pumped in and out of the cooler. It might be plugged. Stranger things have happened. One more thing to look at if you cannot get the tranny cable to work like it's supposed to is this: Ideally, the lever on the carb and the lever on the trans need to have the same "ratio". Measure from the centerline of the shaft(s) to the hole(s) where the cable hooks onto them. Both levers need to be the same length.