Techinspector is right.
The parts are out there.
Our '51 Ford is mounted on a 2000 Chev chassis, so we used a Chev rhd power steering box in our conversion, coupling both steering boxes in tandem.

Lamin8er is right too; you're not constrained to utilising a standard Ford box, virtually any rhd box that is strong enough has the potential to be adapted.

Good luck...looks like an awesome project!

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