[quote]If I recall correctly, even with the original pans, the seat was offset enough that it rubbed on the carpet (can anyone confirm that for L model seats?). I think some reshaping of the seat is in order, though I suppose one could just live with it as the only time I move the seat is when I remove the bulkhead cover.[/quote
On our '72 L model seats (early 3-piece style), the passenger seat is on stock seat adjusters & floor spacers, and is now offset 2" towards the door. It doesn't touch the side upholstery although it's close. Are you sure those are stock seats, adjusters and have stock spacers under the adjusters? Because of the inward 45 degree angle of the inner side structure, if the seats are lowered, the clearances automatically get closer.
You can avoid removing the seat(s) and rear bulkhead upholstering when working on the engine by simply sawing the bubble section loose from the main fiberglas panel. The mod goes clear back to the '80s. Two different articles were published over the years in the POCA Newsletter. The bubble's upholstery is separate from the rest of the vinyl, and can be removed & reglued on the separated bubble, and the bubble assembly mounted to the firewall with velcro. Then when you need to access the front of the engine, only the bubble and inner door need be easily removed. It not only looks stock but is far more convenient, some GR-4s had this mod as-received from the factory, so a case can be made that- like a dropped battery, it's a factory upgrade. Figure on spending a Saturday afternoon doing this simple mod.