Here's where I'm at with the van at the moment.
This is the other side of the van that I haven't paint-stripped yet, you can see the small pinhead sized spots of rust coming through.
Underneath the paint there is the phospher etch coat and you can see the cobwebbing of rust in it which is coming through in the above mentioned pinhead spots.
I'm gonna treat it with "metal blast" and see how it reacts if it doesn't remove the rust completely I'll just sand it back to bare metal. I'm tempted to just sand it back to bare metal anyway just so I can be sure there is no rust. I'm sure current anti-rust primers must do a better job than GMs 70s treatment.
I've also sanded back the rear floor to bare metal, welded up the smaller holes and repainted with a zinc "cold galvanizing" spraypaint.
There are a few bigger holes that I fibreglassed over tonight. I am getting a scrap van soon and I'm gonna cut the rear section of floor out and panel bond it to the current one after filling all unnecessary holes. It will then be painted with stonechip paint from underneath and the gas tank put back in which has allready been painted with stonechip.
I did the same grind back and repaint on the front end and around the windscreen but repainted with rust bullet as it's more prone to rust there and I think rust bullet is the best anti-rust paint I have available to me.