JD, et al,
The problem with putting a lathe on a rolling tool chest has to do with "rolling", not with "Tool Chest". If you remove the rollers, or provide outboard legs with leveling pads, it should work fine.
JP,
The top of the original cast iron leg stand and the hardwood chest for the 24" (42" bed) was 45" wide. 44" would probably work fine. Or you could build the top up to just a fraction over the lip that runs around it and then put a 45" wide top board on top of that.
Robert D.