Hi meehal. Here's a post from my build thread where I used it.
Did a couple of things today, using the new products.
Firstly the tank, I used the resto kit...I forgot to take a pic of the inside of the tank before I cleaned it, whoops.
The tank from the 68 Deluxe

Patch all of the holes prior to treatment

The inside of the tank after the "Marine Clean" and "Metal Ready" process, ready to paint

I didn't know how to deal with that fuel pickup filter. I couldn't seem to catch the end to remove it, so I just ignored it and I will manage that part later...I blew compressed air through the pipe to at least keep the tube clear after I applied the paint.
Perfect fit. The tank doesn't need to be dried between the Clean and Prep phases, but must be bone dry prior to applying the paint. The trusty hair drier sorted it out quickly.

I used line trimmer line inserted into each hole (made larger with duct tape if required) in order to ensure I didn't seal the holes that need to stay. I then sealed further later with duct tape.

The paint is silver in order to aid vision to confirm complete coverage once applied inside the tank.

Keep mixing until this is one solid colour.

The inside of the tank after the paint has been applied, swirled around for 15-20 mins to ensure even and complete coverage; then emptied. Note the river of excess paint I am guiding to the hole to drain. Tip - gaf tape a vinyl/latex glove to the tank neck to catch the excess, just like I didn't.

A few minutes later - looks like good even coverage.

The fate of the original fuel filter - still have to deal with that!

There's a video I shot of the inside that I like. Sounds unnecessary but gives a good indication of the result immediately after application - I'll post tomorrow, along with the update on the polishing.
Given what you've described, I'd think it could be restored, but it's up to you obviously.