Are we talking a T-smoker? As in 30 gal vertically on the bottom for the firebox and the 55 gal horizontally on top for cooking chamber? Door on front of 30 for adding coal? Sounds like it'll work to me. Have to make sure your doors seal up really well to retain heat and smoke.
UDS'-55&16, Akorn, Bar-B-Q Kettle, Drum Grill, miniWSM, cobweb-covered gasser. I'm JD.