[midniteblues]

you can get the rivits out and run a 7/16 tap through the holes without drilling them helps keep everything snug.

i will say the tap will not take a full bite into the hole but it will leave a good enough thread too be able too snug the metal together without useing a nut
(just sayin)of course your gonna wanna put nuts on.

you can attack the rivit with a combo of a cut off wheel/grinding disc,drill,or a cold chisel &bfh.
what i found too work good was to cut a x into the head of the rivit and knock it off with the chisel.of course you could drill a hole an knock'em off also