Sounds like a good solution Niles. What kind of roll bar(s) are you running? We went with dual roll hoops which allow us to use a pair of leftover Porsche 914 seats which fit very well and look right at home with the dual hoops. The dual hoops also give us a good location to which we can attach the shoulder harnesses as shown in the following photos:
http://www.pbase.com/mjb2/cobra_seatbelt_mounts
Much like Richard's solution but without the bar running between the seats. The high back seats give us peace of mind, as do the two hoops. The seat belt mounts were made out of Chevy 283 connecting rods with standard bearings. They fit the 2" tubing perfectly and the bearing material should be soft enough not to damage the coating on the hoops when the car is finished. Finally, the allow us to position the shoulder harnesses properly with respect to our shoulder height...
Mike