Cal buddy, I wish I did have an encyclopedic knowledge of the subject, but I certainly do not. I would wager that the seats frames would be very similar between the 240 and 260, but not sure about the 280. THe good captain here has some valid points. I would look on ebay for some Z seats. All you need is the frame and rails. You can order foam and covers from many places. I would take your time though and budget some cash for the job. I wager to source the frames,rails covers and seats and have them done at good shop, you are looking at 1000 dollars. If you do the upholstery work yourself, about 500. They add up, but think of it this way. You have to touch those seats every single time. WHen people look in your car they are one of the biggest things seen. Investing in seats and good carpet really jazz of a classic car and make it a nice place to be.