Well the dip is interesting and since sulfuric acid has two acidic H+ and soda ash is a mono-base, that solution is being set up as a buffer to keep the acid from being too strong since the soda ash would neutralize the acid if added in the right amount. If I had to I could calculate the amount of sulfuric acid and the grams of soda ash needed for 55 gallons, but it would depend on how strong the acid is as you buy it, Sp.Gr. of the sulfuric, purity of the soda ash etc. So unless you can get the recipe from that shop I would not try it, besides what do you do with 55 gallons of dilute sulfuric acid when you are done? There is a chance you could get into real trouble just trying to flush 55 gallons of acid. The summary of several answers is to sand blast, grind or sand the parts and then replate a few non-srurctural parts and paint the rest.

Don Shillady
Retired Scientist/teen rodder