I would seriously consider a different motor for a chinook. I have a 78 w a 20r, and that thing needs at least a 6 cyl in it. I've toyed with the idea of putting my hybrid engine in it, but it (the truck) is too damn heavy and un-areodynamic. I wouldn't really reccomended putting an aftermarket carb on it. It's going to burn a bunch more gas than it already does. I bet a 5 speed would be a better swap.
I'd go with a 22r/20r hybrid build, cam, exhausr and carb with ignition. looking at doubling the power..and it keeps it simple and reliable.
A 5 speed swap is something I'll probably end up doing aside from any possible engine upgrades. I also have spare sr20det in the garage that I daydream about swapping in there as well. Turbo camper?
Hey, I'm in a similar boat (78 Micro Mini), and am looking to do a similar build for some more power. Have done the smog delete, Weber 32/36 electric and now on to exhaust. Did you ever get a header and if so what brand/model did you go with? My stock manifold is cracked, warped and way beyond shot. Don't really want to drop a ton of money for something that may not fit, so any tips you've got would be awesome if you've been there, done that.