If you are going to be running old US or UK chisel and bit sets, the collets will work, as the bores are standardized to the drill diameters. If you are going to use some of the current Japanese tooling, you will find a drill chuck setup invaluable. The newer stuuf is less standardized, and drill diameters are off. Also, newer drills are generally too short to run properly in the collets.
Interestingly, the Oliver is patterned after, or used the castings/design of the Greenlee manual machines for the most part.