Some more feel-good stuff. Here is the engine block after being hot-tanked. It will never be this clean again. Should I polish it? Advance Auto Parts had a bottle of "Gasket Remover" that you spray on and let sit, then carefully scrape off the gasket. I'll be trying that soon. The hot tank chemicals weren't powerful enough to remove the residual gasket material. The shop said that the EPA took away all their good chemicals and left them with "Lemon Pledge soap suds."
That explains how you could Hot Tank an alloy block. In years past the caustic hot tank stuff would have turned your alloy block to mush. Aluminum blocks were always cold tanked if I remember correctly.
As far as Gasket Remover goes my guess is it's nothing more then paint stripper. That's what I use on tough gasket residue & it lifts the stuff no problem.