Hi James,
Be careful when you choose the seats and don't forget to get info on width of the seats, mounting parts and total height with the mounting parts. When I was improving my replica and my upholsterer was taking ages to start working on my seats, I thought about that possibility, but if I went with the faithful repros of original seats (like the ones you find in Stoddard and Tweeks) I would increase ride height, which would mean that my legs would hit the original vdm wheel that I installed or I wouldn't have enough head room. In the end, I decided to wait a few more months for the upholsterer to start the job and another few more months for him to end (phew!, I say; he took 2 years to deliver the job) and even in the end too much foam in the seats resulted in hitting the wheel.
Best regards and good luck.
Miguel Caldeira Proen