Looking good. My two cents and how it works for me.
I have a S10 Ext. cab, 406 SBC, 750 Edelbrock carb, 700R4 w/2800 Stall lockup converter, 4.56:1 rear, 32" tires. My cam is a Comp XE 274. It has a good sounding idle and carries 14" of vacuum at idle @1000 RPM. It will pull down to @800 RPM with the AC on in gear and still set there and idle.
Around town cruising, I run in 3rd gear, unlocked. On the highway, at 60MPH, it runs about 2100 RPM locked up. When I go through a small town or have to slow down much, I usually shift to 3rd, which also unlocks the converter. If I don't, it will fall off the cam and start bucking a surging like leaving a manual trans in high gear at to slow of speed.
On the highway driving 55-65 MPH it will get 16 MPG. I'm in the process of tuning it with a recently installed WB O2 sensor. I think there is more mileage to be had, not much but maybe 1-1.5 more.
I think the key is to insure your highway cruise RPM is at a place where the cam has smoothed out and the engine is starting make big torque. Also have your timing in as soon as you can get it. Mine is all in at 2800 plus the vacuum advance. My total is 36*, not counting vacuum advance, so I'm guessing it's got at least 30* at 2100 RPM, where I cruise.
If you do a lot of interstate highway driving, you could get buy with a higher rear gear,like 4.11, etc. But that would effect your low speed cruise and in town behavior.
I hope my experience helps you, these trucks are hoot to drive with a V8 in them.
Be very careful of your cam selection. It is crucial to your overall success with any combination.