Well your
1954 has all flat panels so any one with the skills and tools could replace any one of your panels. I would suggest asking key questions like...
1)
Are they going to buck rivet or olympic rivet the panel on? Buck riveting is the preferred method.
2)
What skin material are they going to use? 2024-3 .032 is the correct material for your trailer.
3)
Are they going to remove interior panels to access back of panel? Again the preferred method.
4)
Do they charge per hour or per panel? Some panel replacement when don right can take several hours, so if they charge by time it could end up costing you a lot more than the bid.
Hope that helps!