If I had a hacked up dash, I'd take a couple of good/clear photos of my dash, showing enough of the dash so that the viewer sees what needs to be repaired/replaced.

Clearly mark the borders of the area of your dash that you want to replace. Make a paper template for the area you want, with "orientation markers" on a standard dash.

Post those photos here in "Parts Wanted". There are members here with unrestorable cabs/trucks, who might be willing to cut up their dash. Be ready to send your template to a responder who says they have clean cut-out area on their donor dash. The seller should send you clear photos of the dash area they intend to sell you. The seller should then make a copy of the template and return original template with the cut-out metal. That way the buyer/seller has a copy of what was ordered and what was bought/sent.

If I still lived in upstate NY, I'd first check with Bob Adler in Stephentown, NY - I do not know if he sells cut-outs, but I know he has a lot of 47-55 cabs.