One thing over another, I'd say Avalon's hash unit power supply should have no problem in handling +40% more current (~20% overvoltage and overclock versus the "stable" 350MHz. But this would mean ~+70 power which I'm sure Avalon CANNOT handle as it is, at least for batch #3.
Which part of Avalon you think cant handle it, just the PSU? Can always throw nice 1kw PSU's in them =) 3module is doable for sure I would think. Or are you saying something else other than PSU cant handle this much power increase?
You can easily install a higher power PS. But cooling is the main problem.