Just depends on "what's available, and of course if you use "swap" conversion mounts, and you break one, you are still faced with a fairly high replacement cost
If you find a later spool mount K, you'll have better designed mounts than the earlier pillow mounts.
Be aware that along about the time that Ma went to spool mounts, "she" also changed the design of the front sway bar, which goes up inside the K in the later cars.
"The cat's meow" would be to find a rust bucket junker 73 or later which would give you your disk brake conversion, spool mounts, and of course get a V8 car. You might even find one with a better (heavier) rear axle, and a set of leafs that you can use to rebuild your rear springs.
