I'm in AZ at about 4000 feet (good old hot thin air most of the time). I've had a couple of modified engines that ran the best with no vacume advance at all (I ended up just putting a cap on both vacume ports). The way I set the timing is to run it up to about 3000 RPM and adjust the timing untill it runs the smoothest. Thats just where they seemed to run the best here (when I took the cars on vacation to places about sea level they liked having the vacume advance hooked back up).

Read the instructions with the Edelbrock kit well before you start. What I normally end up doing here is to first try a set of lighter springs under the power pistons and see if that helps before I change step rods. After that if its still rich, I start going with larger step rods (if it's too rich). As far as the shooter goes, normally it can be adjusted enough with just the holes in the linkage.

A couple of other things I have found on the Edelbrock at this altitude and temp are

1. To prevent the carb from flooding over the floats like to be set a little lower than the factory calls for. I'm guessing that it's a combination of the high heat and altitude that causes the gas to expand a little more than the factory anticipated. Don't go overboard the gas still has to be high enough to go in the port (slot) that fills the accelerator pump well.

2. Personally, I've never had good luck with the spring loaded needle valves Edelbrock uses. If you have problems, your kit should come with non-spring loaded needles you might want to drop in. If not the cheapest way to get them is to order them separatly from a parts store. What is interchangable are the needle and seats from an AVS of a Chrysler product (like a 1968 383 Road Runner).

Don't expect a lot of miracles you've got a lot for truck and a relatively small motor.