It's real easy to do. The mount bosses on the '62 motors, were 6" back from the front of the block. The 302 bosses are 7" back and offset left from the right.
Just make two steal straps about 8" long out of 1/4 steal and drill three holes . . . to mount on the original motor mounts and also to mate up to the 302. You just need to turn one of them facing towards the back of the motor.
The picture below of just the mount actually has the strap on the wrong side. It was just for the picture so you could see the entire strap. The second picture shows the whole thing mounted on the motor. The mount on the other side will need the strap turned 180 degrees because the bosses are offset . . . or is it the mounts are offset?? Can't remember.
I've been driving (not so softly) this '62 with the setup shown for about 8 years and no problems.
Just make sure the strap is on top of the motor mount so the weight of it all is supported.
Hope this helps!