Help with plasma controller build

[m_c]

I'd probably err on the side of caution and go for a 40V toroid.

Theoretically, 40VAC should give 57VDC, and 45VAC give 63.6VDC, however that's assuming perfect mains voltage of 230VAC, however it will more than likely will be higher.
Allowing 10% gives a reasonably safety margin.

Typical current guidelines IIRC are 50% of the total of maximum motor current for all motors (that gecko guide I linked to previously covers it), however it's always good to go slightly bigger, and from what I remember there's not much price difference between a 500VA and 625VA toroid.

Rapid Online should have everything you'd need. I normally use RS, but I've got an account with them so I get free postage. Airlink Transformers can be cheaper for the transformers.