[Amps] class "A" RF amp question

[kenw2dtc]

If one were to build a class "A" RF tube amplifier capable of producing an 
AM signal of 375 watts carrier and 1500 watts PEP, what would be the plate 
dissipation required by the tube?  (I know how stupid and inefficient this 
is, but I really would like an answer).

As background, I have an AL-1200 (3CX1200A7) which starts to flattop beyond 
375 watts of carrier at 100% modulation and this amp is class "AB2", so I 
know class "A" would require significantly more dissipation than 1200 watts.

73,
Ken W2DTC