64 pushbutton tranny to 66 slant six

Imperial Services has a conversion "service" to convert a PB shifter to a late trans. Be sitting down when you look at the price, and then it takes several months to get the part back.

If you are getting a later trans, be aware, if the trans is 68 or later, it will not fit the 66 engine/crank.

Brian, you don't have do a lot to the trans, to make it live, and the mods are easy. My 170 motor makes 358 ft lbs torque at 2900 rpm. And I am using a 65 trans.
Also a 64 trans with a 66 engine does not require a custom converter.
A 68 or newer trans, with a 67 or earlier engine does require a custom converter