I'm not even going to show you a photo of the start of my firewall ridge removal! I sectioned off about 6 or 7 inches, I used a cutoff wheel to make the section by cutting directly into it. Prior, I had sandblasted (aluminum oxide) the upper area. Looks like crap, the metal coming downward doesn't look too great.
I put a weld on the top portion (my weld burned through a bunch), but made it almost complete with the exception of a few pinholes.
I put a cutoff wheel on my angle grinder and cut off the rail that I have sectioned off. I welded that, if you want to call it welding. I'm actually a fair welder-er, but this is making me look BAD! Cutting the rail off does kind of leave a larger gap than I was contemplating.
I ground on that weld for quite some time, and now there are a few larger pinholes that I'm going to have to fill like smaller firewall holes.
I should jjjust (starting to studder!) weld a lip back on and call it a day!

After a well derserved cup of coffee, I'm sitting here recooping my strategy, of course with ya'lls help!
How about this, as difficult as it may sound, why can't I weld from inside the cab, at least 3/4's of it is accessible(I think). There's a perfect little "V" where the panels adjoin. However getting it clean for welding may be a pita. Plus access above where the steering column would be a pita too. Anyway, I could stand on the floor of my garage and work up through the floor panel fairly comfortably. I have a ventilation setup to suck out the smoke.
OTHERWISE~ advice would welcomed