I think you might either come short of 55# or end up with a lot of set or chrysaling.
In the future, you can make the bow wide at the fades even if the crown comes down to within a 1/4" of the belly surface. Wood is 3 or 4 times stronger in tension than compression, so a crowned back that is thin on the edges is usually fine.
I have made some good bows of black locust, but I learned that the wood needs lots of belly width to handle the compression stresses.
Jim Davis