Easiest way to remove upper rear shock bolt

[TC70C10]

I just got a sweet deal on a 85 K5 one owner on New Years day. I've been going through it and replacing parts/maintenance that has been neglected.

I'm working on the rear shocks and the upper mounting stud has what looks like a rivet instead of a nut. I grinded it off last night and got the washer off. What's the easiest way to remove that mounting stud. The nut is inside the frame overtop of the gas tank. I'm thinking about taking the sawzall to it an be done.

It looks like I can get a breaker bar on a 3/4 in open end and try to break the stud loose from the shock side.

Thanks