Guess I'm gonna hafta go back thru the how to on the marine manifold. I didn't think there was too much precision machining involved. Drilling and tapping a couple of pipe thread holes was the main thing I remember. It's been a while since I read it though. Time for me to do some re-research.
If one was determined to go with a Holley Stealth Ram, TPI, SuperRam, or the Edelbrock Pro-Flo XT (7138) they could buy the bracket kit from GM or go to a salvage yard and get the accessory setup off of a TBI 4.3 (I know 91+) or TBI 5.0/5.7 (I'm thinking 93-95). They are all the same, and will bolt on with no issues. Get a hose set for the V8 TBI truck and you should be pretty close...unless GM hosed ya on a metric accumulator on the newer trucks.
A word of caution though, if you go salvage yard hunting for all the goodies don't forget to bring a power steering pump pulley puller with you or you will never get the bracket off the head.
I'm curious to see how the Edelbrock Pro-Flo XT (7138) stacks up to the HSR. One difference is the Edelbrock unit uses the LS1/L31 style throttle body as opposed to the old twin butterfly of the TPI era. Plus it looks to be more of a as-cast version as opposed to the HSR...which looks best when polished but that doesn't fit with the underhood look of these (well...at least mine) trucks.