Can I run an 80w MV lamp with 2× 40w fluorescent chokers in series?
You mean the chokes will be in series with each other or you mean in series with the lamp?
The chokes should be parallel to each other and then this combo in series with the lamp.
The lamp could be slightly overdriven, but I dont think that is anything to worry about (MVs, being unsaturated vapor concept, are rather tolerant to current variations, no thermal stability issues).
These fluorescent chokes are not that much efficien against proper MV ballast, but the MV is not used for any high efficiency either, so likely no problem in that either...
