Good Evening, Melanie,
For what it's worth, whenever I occasionally process a contact sheet or work print in a drum, I make sure that I have plenty of solution. After all, for B & W, cost is not really a factor, and there's no harm done by having a little too much developer or fixer in the drum--unless the amount is so great that it slops out during the rotation.
For 8 x 10, I'll use at least eight ounces, but ten or twelve ounces causes no problems. After each step, I pour the solutions back into their containers and reuse them for the next print or two or three. I suspect that eight ounces would actually be enough in an 11 x 14 drum, but I'd probably plan on at least sixteen ounces.
Konical