A couple of points, Bob.
First, Knotts is very partial to their cars. No, I don't think converted 6500's trailing their two C-19s would be acceptable.
Second is the seating. I'm sure you want to make a profit on the San Juan if you get it up and running. Don't look now but it takes 100+ rider trains to make a profit. An historic San Juan with a baggage, a mail car, a coach and a parlor, if equipped with swivel seats, would only hold about 30 patrons if it were full. No, I think you'd have to have 44 seat coaches and not 20 seat ones to make a go of it. You'd also have to increase the length of the train to the max a 480 can handle to break even, probably three coaches.
Sure is nice to dream about though....If we could just get the mail contract back.........