Yes, the early cars are 16 x 1.50. Note, however, that the threads must be deep enough to accommodate the spring deal that allows the rod to be lifted up over the reverse plate. For example, although late-model Camaro/Firebird knobs are made in 16 x 1.50, they generally are not deep enough.

I ordered a custom shift knob from a company called Epco. Their standard knobs come in 16 x 1.50 (just order the threads as deep as they can make 'em), and are available in a variety of colors and diameters. Mine even has the correct shift pattern engraved. Just imagine buying a shift knob from a company that makes bowling balls!

They're at http://www.epcomfg.com/shiftknobs.html

Here's a semi-decent picture someone took last weekend: