You can rule out the Rally Sport. For the base LF7 (327/210) and the optional L30 (327/275), the BP axle (2.73) came on non-RS cars. (RS cars got a 3.08.) And as memtioned before, you don't have the factory hole for the 4 speed, so the car came with a Powerglide automatic transmission.
So no way to know for sure which engine it originally came with, but the more common engine by a long shot was the base LF7 (124,870 vs 21,686 L30's), so that's probably what the car started life as.