To the best of my knowledge many damage calcs have the ability to edit base stats and typing (such as
Honko's) so if you'd like to try that for your damage calcs, there it is.
I *highly* suggest not using Heat Wave on anything that has access to Flamethrower. There is not one set on Smogon that would advise a 5 BAP increase with a 10 Acc decrease, it's a pretty bad trade-off.