Sorry, I just don't see this. Is there some penalty you're applying to the Tempest? Under 20,000 ft, both models of Tempest have it all over the F4U, in pretty much every measurable statistic. In speed, rate of climb and armament the Tempest is clearly ahead; range, wing loading and power loading are pretty similar; and the Tempest's cockpit view was clearly superior.
In rate of climb above 18000 ft, Tempest V and F4U-1D are as close as possible (
chart,
chart). The F4U-4 climbs equaly as good as Tempest V under ~17000 ft, between 17000 and ~23500 ft it the F4U-4 has an edge, and it is much better above 23500 ft. (
data sheet). Eg. at 30000 ft, it climbs at 1600-1800 ft/min at max engine rpm, while Tempest V is good for 750 ft/min at that altitude. The F4U-4 is also faster above 20000 ft, Tempest having a 10 mph edge under 15000 ft.
The Tempest II is simply in a different class to the F4U-1, and even the F4U-4 is only just a match in some statistics. The Fury is further ahead again.
Tempest II (
perf chart) is indeed a better performer than any F4U-1, I stand corrected. It is also better than F4U-4 under 15-20 kft, but it was slower above 25000 ft, and climbed less well above 17000 ft.
Sea Fury is like the a bit better Tempest II - it is again a better performer than F4U-4, this time to 20000 ft, give or take, the F4U-4 better above 25000 ft.
The F4U-5 was again better than either of those listed above, and Fury (with Sabre VIII) was also better, at least under 20000 ft. Unfortunately, the Griffon Tempest/Fury didn't materialised until too late, to combine low drag of Tempest/Fury with ample power at altitude.