I must be on a bunch of "ignore this user" lists, because it seems like every time I post, someone else will the post the same info later.

I own a 59 Coronet. Was originally a 326/Powerflite, now a 1964 Chrysler 413 with a 62 Chrysler Torqueflite worked by a 59 Dodge Torqueflite pushbutton setup and a 63 Chrysler shift cable. Have factory 1959 Chrysler motor mounts/brackets up front, and the original 59 Dodge trans crossmember with a 64 dodge trans mount extension welded to it that holds a 64 Dodge trans mount. E body 8 3/4 rear.

The 62 Chrysler trans has a parking brake drum setup on the back of the trans like the 61-earlier trannies did, but I had to use a 56 Plymouth backing plate for the 59 park cable to work on the 62 park brake.

I thought my experience with my own 59 Dodge as well as my 56 Plymouth with a 277 poly and Powerflite would give me some insight into the OP's question, but maybe not.

Carry on.

PS: 1961 was last year for Powerflite.