Here's my take. If you want the ultimate "Wow" factor yank the 408 and drop in a GenII Hemi. Done!
IMO it's hard to beat an STR12 for a small block in terms of under hood glamor (EXPENSIVE!), but they can be a trial to find, install, and tune properly.
If you want the car to perform to it's limit you'll likely find the best way to get there is a single 4 barrel.
For vintage look I'd go with a Thermo-Quad, you don't need a Comp series unit either (they work great but are not very street friendly). For a more modern approach it's hard to beat a Holley 950 on a stroker small block with an aggressive cam profile.
Six packs are great dependable power makers as well (and if properly tuned) will perform with nearly anything, but it's a lot of extra expense and hardware to get to the same goal a 4 barrel can reach, plus, if you run a stock oval air cleaner a 4 barrel looks basically the same as a Six Barrel when all covered up, all that money and now it's all hidden, that goes double if you run a Shaker hood.
Dual 4's are sort of the same story, not really needed but if you like the look and don't mind the added expense you won't likely lose (unless you over carb the engine) or gain any performance over a well chosen single 4 setup.
Almost thought you were refering to my car for a moment as I pulled the STR12 off and installed a 950hp Holley on a hand ported M1.I have only run the 950 on the street so far but will see if I gained anything in the spring when the dragstrip opens.I do Miss the WOW factor of that crossram and I had absolutely no issues with it. I also installed an Indy Mod man intake on a car I am building for a friend on his stroker small block with the magnum heads.But have not been able to try it out yet as the car is in pieces at the bodyshop being painted.He also bought the single 4bbl top plate for the intake if the 2 4bbl combo doesn't work out.
