Greg, you've got a real can of worms here. One thing you may not have
considered yet is to generate sufficient 220 3phase and just convert it
to 440 3phase using a (biggish) transformer. Or, you can convert 220
single phase to 440 single phase and then make a 440 phase converter.

A guy in our area recently did just that. Big transformers sometimes show
up but they often aren't cheap. I have one that might be big enough for you,
and might be cheap enough for you, but it's in LA and I won't be running
a vehicle down there until spring break which is a few weeks away. I don't
have the specs on hand, either. I do have 'em somewhere, though.

To email me, either use or go to the link:
http://www.tinyisland.com/email.html

Grant Erwin
Kirkland, Washington