early A body engine swap

The trans mount looks correct for 64-66, rubber is cracking not sure if split through, you will have to check. rear leaf spring front location looks stock. Time for testing, install the thicker insulator & check for clearance and driveline angle. If pipe is hitting frame, you have a few choices use thinner insulators and modify trans mount down, modify header tube for clearance, my last option is insert shim between K frame and frame rails. I would not use sold mount if driving on street.
Thanks for all the tips! I still think I'm going to order some thinner mounts as backup, and then start tearing into it as soon as I get the car back home. I'm also keeping an eye out for the shorter engine brackets and even different set of headers.