I finished this up this weekend (finally!) and thought I'd share how I did it. There are so many ways to do this that some of this info and picture stuff might be useful to somebody. First, here's where we started:



The car is remarkably rust-free except for these pieces, which were soft and flaky. Since I already had the nose off and most everything to pull the body, I couldn't, in good conscience, put it back together without addressing these. After lots of research, I decided to just lift the body 6 inches or so. To do this, I used a 24" 2x4 on each side (cut to fit the edge of the door channel) and bottle jacks. I set it back on some more boards resting on the fame and removed the old pieces. On one side, I was a able to just drive the old bolt up through the body. This was DUB's suggestion and worked great (a couple smacks with a hammer broke the rusty parts and the whole thing came apart). On the other side, the mount bushings, bolt and reinforcement were fused together, so it took a cut-off wheel to get everything free.
In the back, there's one rivet you can't get to easily. Again, at DUB's suggestion, I unbonded part of the rear inner splash shield. This got me enough wiggle room to do what I needed. (Note this pic is from later in the process with the new parts in, but you can see me pushing the shield so I could reach behind it).



Next, I worked from the inside (it's a convertible, which means working around the spring and hinge). I used a dremel to cut the rivets on the inside reinforcement. Then I worked a bottle jack into the cavity and put just enough pressure to pull the bottom reinforcement out.



To be totally correct, you need to use rivets to put things back together, but that can be a bunch of extra work for no gain (on a completely non-original car like mine, at least). I saw a couple people use weld-mounts, which look very original from underneath and are way easier to install. Here's what I used:


Really, 10-24 threads would have been better, but this is what I found for a reasonable price on Amazon... It takes dexterity, patience and skinny arms to get all the nuts on and tight, but here's what it looks like from the inside when it's done:



Before I installed the new parts, I etched them, used POR-15 then the POR "Hardnose" paint, then scuffed them up. I also took the opportunity to clean up under the fender wells. After re-bonding the rear splash guards and shooting some undercoat, we're ready to drop the body back.



On the #4 mount, I'm just going to feed the bolt down from the top, like many others have done.
Overall, this was not something that could be done in a weekend. Just raising the body is a job all by itself (not to mention all the "while I'm at it" things that you decided to do while the body is in the air...). But after lots of looking and talking to people, I decided this would be the best balance between getting the job done right and not turning it into a full-on restoration.

 

Hi EM,
Looks like some good results for work in a difficult location!
I think many people will find your pictures useful since this is often a rusty body mount on cars.
Regards,
Alan

 

Nice job, I tried to do the rivets and punch route which was hard. I believe your way looks great and will support the reinforcement bracket as well. A lot easier and effective.

RVZIO