I have seen 3 of those Holley Webers on several inline engines, the owners claimed they worked quite well.Personally, I don't care for the Holley Webers,but they are the right size and available for less than silly money.Also seen 600 cfm Holleys and Edelbrocks on big Jimmy's, Sixpack, who posts here, has such a setup.You'll supposedly get better mixture distribution from a multi carb set up VS a single 4 bbl., but from my experience on street engines,the advantage of multi carbs is just bench racing stories.
If you want to buy an intake, check around on the Inliners site for info,most GMC stuff is kinda rare.Building your own is a great idea,with 3 carbs relatively close to the intake ports, a heated manifold is probably not necessary unless you plan to drive in real cold weather.Another carb to consider is the Holley single barrel 1900 series as found on 6 cylinder Mopar and Fomoco engines.Or the Holley 2bbl "Bug spray", designed for WV's, they are on Ebay, new ones for reasonable money.Another choice is the common two barrel 2300 holley, available in 350 and 500 cfm ratings, which flow around 250 and 330 cfm when rated like four barrels.Many of these carbs will require some tuning to set up properly and linkage to be fabricated.
