I have this book (or rather booklet of 33 pages), where a report by NAS Anacostia to BuAer is quoted. The weights of XF5F-1 given there are 8,107 lbs empty (incl. residual fuel and oil) and 10,132 lbs take off weight in fighter configuraion. I mention this becasue of difference between the chart linked above and 383 mph floating around as supposed Skyrocket's top speed. Since weights in the chart are lower than in the NAC Anacostia report dated 17 Feb. 1942 it might be that not all aerodynamic improvements found in the final configuration were implemented when they measured 358 mph at 17,300 ft. Then again gaining 25 mph sounds kind of unlikely to me without increase of power, unless 358 mph was achieved in original configuration.