BTW, I have a manifold and adapter to put a GM throttle body on it if you are interested... Howell can make you a FI kit for it, or you can junkyard a kit from an early '90's 4.3L with 5.0L injectors. You'll need to swap in an HEI distributor out of a later 250/292, but that should allow you to put the FI compatible spark controller in and you're set!
I will ship you the manifold if you want it because I'm done with it. (Scrapped my truck out several years ago.) It is from Brazil, and should bolt right to your factory exhaust manifold. Skip exhaust headers of any brand... They all SUCK.
(Oops, I'm reading the thread backwards. See you already EFI'd it. Nice!!!)