5FP7 project starting with the focusing coil.

[ppppenguin]

I haven't followed your calcs in detail but here's a quick sanity check. Primary voltage is 54V. If it was a 50Hz design that would allow 4x54=216V on the primary. Hence the number of turns you need should be a little less than the original 240V primary. You've got about the same number so that leaves a bit of margin which is good, provided you can fit all the wire on the former.

Heating in the copper is based on RMS current, the usual I*I*R, so you can rate the wire for that. Peak current not relevant. Allow a little margin.

The big unkmown is what the DC in the primary will do. This is beyond my knowledge. Best wait for Ed Dinning to give his opinion. Pushpull won't have DC in the primary so that's safe.