Could you run a 80w me lamp on a 100w Mac CWA ballast as I heard you could do that but not sure if u can. Can it also work for 75w lamps.

An 80W MV is 0.8A at 115V - can't advise as I don't know the specifications of that ballast. It needs 200V or so to strike, though.

From what I understand, North American 100w H38 mercury vapor lamps run at 130v 0.85a and North American 75w H43 mercury vapor lamps run at 130v 0.66a. When I performed tests involving European 80w mercury vapor lamps on North American 100w H38 mercury vapor CWA ballasts and HX ballasts, I have noticed that the lamps were slightly overdriven and the ballasts did not seem to heat up that much. The lamps operated at roughly 1.0a at 130v according to my rough estimate.

Not really close enough in my opinion.

Overdriving by 25% is quite a lot, it will shorten the lamp life significantly.
So at least some chance would be with the 0.66A H43. Operating underpower just causes lower performance (efficacy), but does not affect life. Plus the 19% underpower isn't even that far away.

I checked a few numbers on the lamptech, and found that the current for most 80w and 100w lamps is the same at 0.8 amps, just the voltage is different