Fuel Fluke

i had a mach 1 that had sat for years/ stranded me on the way to show it off to my friends the tank was full of scale and varnish i took the tank out of the car and threw some lug nuts over in it and shook the hell out of it to break all the crap loose i then kept washing it in a parts cleaner till nothing else came out /poured a gallon of lacquer thinner in it to cut the varnish reinstalled and all was good!

I washed the tank out with water and let it dry.... tried to shake the tank and see if anything fell out which it didn't. I examined it with a flash light and didn't see anything that would be of concern. Maybe I over looked something that I thought was ok. After today I know I did. I'm going to order a new tank just to make sure. That would be my best bet and rule out one thing that might be the problem. Here goes more $$$$$. If I didn't have a Fastback with the let down door in the rear I would buy a fuel cell.

Do they have fuel cells that mount under the car? The reason I'm asking is I had to enlarge the sending unit hole in order to get my Autometer sensor in the tank. So if I get a new tank I'm going to have to cut the new tank.... don't really want to do that.