64 Dart motor mounts for a 360 conversion

All you need is 64-66 mounts.

Yep, with a few washers on the driver's side for a spacer on one bolt, and mod the passenger side mount as shown in #3 above. Or, you could just use the passenger side bracket as is if having only two mounting bolts is OK with you.

Washers on OEM 64-66 driver's side rear bracket bolt:

20200223_232128.jpg

Modified passenger side bracket:

20200816_172540.jpg