Fuel tank restoration

Non Mopar so forgive me.
I have a fuel tank id think its about 10 or 12 gallons or so made out of steel for a engine drive welder (1969). I don't think I can source a new tank or even a decent used one and a aluminium replacement is very expensive, more than I want to spend
My tank has some rust on bottom, doesn't look to bad but bad enough to screw up the carb
I bought one of these 3 step restoring kits, the last step being a paint/covering type sealer
Has anyone had any luck with them on a old tank
The problem with the sealer is that if you don't continually rotate the tank, the sealer all lays on the bottom, lumps up, dries and eventually comes apart. They use to push that stuff to repair motorcycle fuel tanks.