Outlaw,
Make sure you mount the shoulder belts at a point that matches or is slightly above your shoulders. Don't mount them to frame rails under the floor. The reason for this is that the belts will compress your body in any forward impact. Shell valley cobras are very close to A&C cars. Use the upper rear crossmember over the rear axle or weld in a cross bar. Your lap belts should connect with grade 8 bolts to the main frame rail (inner) and the outrigger rail (outer). I hope this helps.
--Mike