I am wanting to know how many ft.lbs the subframe bolts should be tightened in a 69 Camaro. I have installed polyurethane bushings.

I think 70ft lbs is the correct amount but, wait until someone verifies that, just in case I'm wrong. Your mounts didn't have instructions?

I torqued mine to 75 ft. lbs.

I thought that it should be closer to 90 lbs or so.....

The assembly manual shows 75-95 ft lbs. I usually split the difference, so I torqued mine to 85.
The radiator support to subframe bolts show 30-40 ft lbs which I torqued to 35.