I'm partial to the Holley model 1904, which is primarily an International and (dare I say it? Ford carb. It also saw use on some GMC engines in the late '50s/early '60s. It does require some alteration, as the throttle lever is backwards for a Chevy, unless you can get lucky and find the GMC inline 6 version. Easy to overhaul, and the jets are the same as the later 2 and 4 bbl Holleys, so they're very easy (and cheap) to find.
Another good choice is the Carter YF. You just have to watch what it comes from. There's some out there that are Ford variants that will run way too rich on a Chevy, some rebuilders will stick them in boxes marked for the Chevy carb.
