I've bought a couple of pair of hoods from ebay for these levers, the same ones that fit the 600 levers from the late '70's.

In a pinch, I've used DiaCompe hoods in brown, and of course now these have been re-popped as Cane Creek brand and widely available in a tan color.

The original gum hoods are pretty nice, but expect to hunt a bit and pay perhaps $30/pr. They don't last as long as newer materials tho.