Theres the back. Figures its rivets, as gsa already etermined :/

Oddly enough, I do have the chainring I want in the correct BCD that I picked up cheap at a LBS garage sale. I've drilled out a few bolts in the past, including in engine blocks, not particularly worried about the skill, more wondering if it'll all go back together with regular crank bolts if I do so.

If its risky, its only a 2 tooth difference, I'll just leave it. The crank itself is as solid as any other I own,and far more so than the one it is replacing, no desire to destroy it.