My old Pica T-28 ended up around 45 oz/sq foot and I was worried it was too heavy as well. It flew fine but it did take a while to tune the CG to get it to slow down as the build ended up quite nose heavy. Slow flight at altitude is a good suggestion as well so you know how to slow it down rather than just flying it in hot. Beautiful Mustang there and I am sure it will fly great.