K-Member

I'd use that early K frame in a New York second.

The spool mount isn't any better or stronger. In fact, you can't even get solid motor mounts for the spool mount K member AFAIK. It isn't stronger. Chrysler went to it for two reasons.
1. Much quicker assembly on the assembly line.
B. If you don't do your due diligence and do maintence, you can have a failure of the mount and the fan can break the shroud.

A motor mount is like any other rubber part on a car. It needs to be changed. If you use the solid mount, they won't break and the car will drive better.

I had my car all apart last year and I wish I had found an early K member. I'm not a fan of poly mounts. When the engine comes out again, that spool mount is out.