I agree, Going longer does not pose and issue. It would lessen the stress on the limbs.
I just wasn't sure if you were shooting for the shortest possible bow.
My bows are usually 50-55 lbs Draw weight @ 28''
I take the Draw length (28'') X's 2 = 56,
56 X's 10%= 5.6
56'' + 5.6'' = 61.6'' is the shortest I go just as a rule of thumb.
I am not a pro at making "shorties" so I don't try to stretch it by going shorter.
The best I have pulled off repeatedly is 8% which came out to 60'' Tip to tip, but these are also a slight bend in the handle.
For me I think a 5' bow is plenty short to maneuver in the woods while hunting.
Depending on the quality of the wood I may add 15% to length instead of 10%
So far the only bow I have broken was the first one I made. I chalked that up to learning to tiller and not rounding off edges.
I would give your thoughts a shot and see how it works out.
Worst case if you miss your target weight, at 64-66'' you would have a few inches to trim off and retiller.
I wish you luck.