I agree with Big Kahuna on this, except that I'd be willing to push it slightly harder than 150 peak. I think it will comfortably do 180-200 watts. 1446s are pretty rugged transistors. I've abused them very hard at times and had no issues (even though you could cook breakfast on the amp).
Anyway, 40 watts peak input is too much, IMO. Big Kahuna's recommendation of 15 watts is much more realistic. I also agree that a low dead key will be needed. 2 watts or less, I would guess,
The "HD" used in CB amplifier naming is generally meaningless, IMO.