Well, I would cut it down to 1" or so wide by 7/8" thick and give that a try for starting dimensions. It might still be a bit too heavy though, but it gives you a bit of leeway. When I want a 50 at 28 elb though, I will go 74" tip to tip (which will end up about 72 1/2" to 73" nock to nock), 1" wide at center for 3 1/2" each side of center ( so 7" continuous width in the center), 3/4" thickness in center for 7" again, than taper both thickness and width to 1/2". Different woods will give different weights, but I use this for ipe and hickory mostly with no problems. If you tiller good with no major hinge corrections or whatnot it will typically come out right around 50 at 28".
