Good questions. I think the locating pin was only there to help you when you installed the wheel and served no purpose once it was torqued down. The rivits should not be a problem either unless they really stick up far and contact the new wheels before the rest of the wheel. You could check this by putting a little dab of white grease on each head, putting the wheel on, torque it lightly, then see how much transfers, if any.

When you say modern wheels, do you mean as in mag wheels, or are you referring to steel wheels? As for the tubeless part, look at your rims inside to see how they are put together. If they have rivits they might leak around there, or maybe not, depending on how tightly they are put in.

Shoot us some pictures of the surface of the brake drum where the wheels touch, and also the backside of the wheels so we can have a better look.

Don

Oh, and welcome to posting!!