That is, unless you are doing a 'perfect storm' airshow climb stunt - huh, Ww?
Are you sure 'standard atmosphere' does not include windspeed?
Did you check out those service Spitfire Mk 8 climb rates..
Maybe we can talk Brad Pitt into putting a race-mill Merlin in his Spitfire..
For an attempt on the FAI record..L.O.L...
Sure, someone could install a high output Merlin into a Spit and try for the record.... The record is held by Rare Bear, whose R-3350 was generating in excess of 4,000 hp when it set the record. All of that said, a service grade Spit VIII averages about 1,000 fpm less than the service grade F8F-1 that set the record in 1946, where it averaged about 6,400 fpm.
Also, the best Spit VIII climb rate in that chart was obtained running 25 lb boost. 18 lb was the standard Combat Power setting, and that boost is reflected in Aces High.