[Captainfab]

If you do not want to go to the work of changing the entire differential, then an OD trans is your only other option to lower your RPM's. A manual trans would be the easiest. If you go with a 700R4, you have the TV cable to deal with. No one makes a kit for a I6 carb to correctly setup the TV cable. You will have to fabricate something with lots of trial and error to get it right. You could go with a 4L60E, but then you will need a aftermarket standalone controller which will set you back about $700, plus another $125 for a TPS kit which will require modification/fabrication for your carb. No matter how you go about lowering your RPM's, it is going to be a lot of work.