I would try leaving the rear brake setup alone since the heavy work will
be done with the front disks.  Regarding the rear end, a 44 is always
preferred over the 24 or 23...

JT

Better check that engine.  '64 Cruisers came only with 289s.
Paul Johnson

Those brakes should be fine, but ask JT if you need to cut pressure to
them (I suspect you might)

nate

For slow flatland driving, I guess the "6" brakes could do if you're
not towing.
Otherwise, I'd go for the axle/brake change.
When you're done, drive easy and get the brakes worn in, then try an
emergency stop on a wide space. If the rearend comes around on you, go
for a rear pressure reduction or maybe harder shoes might do the trick
and will last longer.
Havig a reear come around is not fun, if it is unexpected.
If uou have in mind using your parking brake in case of front brake
failure, keep0 the release on or you might come around!

I had to teach the instructor that in my :"naughty boy" remedial
driving course. He hadn't tried it.

Karl

If it were my car I would upgrade the rear brakes to the V-8 brakes,
upgrading the rear wheel cylinders would eliminate any pressure issues.