Toroidal Transformer Help needed

Anybody know how to calculate the windings and wire sizes needed to
wind a
toroidal transformer ?

Here are my specs for the power supply I need to build

2.5 kva total output approx

120 volt DC 20 amps final output

I believe I need an transformer that will put out around 83 volts AC
before rectification ,at what amps ???

My input voltage will be residential 220-240 volt three wire
I need to measure what we have here.

I found a place that will sellcores and material to build
transformers
I have also asked them the same questions.

Pretty cool site Alphacore.com

Any help would be appreciated
Thanks
sspeed33317