On my 56-60” d/r form, .005 equates to about 5#. Im guessing a little less on the longer bows like you are building, but probably still about 4# per .005.
So I’ll say 8# plus an additional 2# for thinner glass for a total of 10# drop.
Then I’ll guess you should gain about 4# for every 2” shorter. So you will gain 8# back with the 64”.
My guess is you’ll hit 50# with the .325 stack. Final answer. lol
But what do I know, I missed weight by about 10# on my last build.
But I also think switching from Gordon’s to bear paw glass had something to do with that