I'm sure it would work, I remember seeing a diy project someone did (Yuri_Rage?) where they got some kind of conical end like that and added more stainless to the top etc. You'll need a stainless welder of some kind (is that TIG at a minimum welders?) and then you'll need to know how to weld sanitary welds, so no bacteria can hide in the crevices... But it sounds like a fun idea...

55 gallons is an odd size, though, 1bbl is what, 31 gallons. two would be about 62, so you're like 1.6 or 1.7 bbl? :P (too lazy to open up calc)