If those Vortec heads have non adjustable valvetrain, you'll want to convert them to adjustable before you ever put them on. You can get a special stud that is 3/18"-16 on the bottom and 7/16"-20 on top, but I prefer to do a proper conversion with a standard stud that is 7/16"-14 on the bottom and 7/16"-20 on the top.
I'm not sure which intake will line up best with the intake ports on the Vortec heads, but I would not buy a dedicated TBI intake unless I had to. A good true high rise oval port intake for a 4 barrel combined with a Trans Dapt TBI adapter has worked better in the past for me.
You'll do better with 3/8" pushrods and guide plates, especially if you're going to run a decent aftermarket camshaft. Since you will likely convert to adjustable valvetrain, you may need to get a set of pushrods that are not stock length. Get the geometry wrong on a big block Chevy and you'll be replacing pushrods, rockers, valves, and valve guides regularly, not what you want to do if you need that truck.
I've successfully used a Comp X4 262H in a heavy work truck with a 454 TBI, and an automatic transmission with a stock converter. However, it had a 3.73 gear, headers, and dual exhaust. It had early model closed chamber oval port heads, not Vortec heads. It ran well, puled even better, and got decent fuel mileage as well. If memory serves correct, it was degreed in at 107 or 108, and the truck liked about 10-12 degrees of base timing.