I have a stunning fillet brazed Bilenky tandem frame with extras for sale for $1650. Here are some pics.
I can sell locally (Philadelphia) or pack it securely for safe shipping to you. Bilenky is near me so I could also get the frame over to him if you wanted him to add S&S couplers or do other modifications. I can answer questions about the frame to make sure it is a good fit for you and your stoker. Here are the specs.
Serial Number: 2002J
Captain/Stoker center to top: 22.75"/21.5"
Captain/Stoker center to center: 21.25"/20.5"
Captain/Stoker stand over w/ 700x28c inflated tires: 32"/30.5"
Captain Top Tube: 22.25"
Captain Seat to Stoker Seat: 25.75"
Hub to Hub: 67.5"
Beautiful three-tone custom finish with some blemishes (see pics)
Frame+cranks, chainrings, derailleurs, chains, brakes, seat posts, stoker handlebar and mount.