Carb jetting for altitude

[Prescott]

Hi everyone,

I've got an all-original 1967 C10 with a 283/3 speed manual/rochester 2G manual choke #7027105. I live at 5500 feet of elevation, and my truck has always run rich. The previous owner had the carb professionally rebuilt 10 years ago, and it runs pretty good, aside from stinking like unburned fuel all the time (out the tail pipe, of course). I am planning to dismantle the carb, clean it out, adjust the float level, and re-jet smaller. I don't yet know what jet it has now, but it's supposed to have a .054" from the factory, so that's what I expect to find.

My question is this: What would be the right jet to order for 5500 feet? It would be nice to have a selection of jets, and try them all to see a happy spark plug (mine are black as hell now), but these buggers are $10 each, so I'd like to get it close on the first try.