Howdy STP007:
Multi carbs are hard to beat for coolness, but they require alot in tuning, both in getting them right and maintainance. And as always, your induction must be coordinated with the rest of you engine/trans/gearing package. The issues/problems relating tofuel distribution on a long I6 are well served with 3X1s
The Offy manifold adaptor kit is really well done and Weber are easily tuned (but expensive). 3- 175 cfm one barrel carbs will have you over carbed, but the progressive linkage in the kit helps to moderated that. IMHO, 3X1s would be a better performance option then either Weber 2V option. The top end with 3X1s is awesome. A Weber 2V, might be a better option for a daily driver- excellent idle, economy, tuneability, and a good power increase.
Based on Slade's experience you might need to lighten some of the return springs on the linkage.
A Holley #8007 4V with 390CFM capacity, progressive, vacuum operated secondaries would be perfect for a small, street six, except that it is next to impossible to situate the carb so that the inside fuel bowl clears the valve cover. If you raise it enough to solve that problem, hood clearance becomes the issue. Modifying the log manifold to take advantage of the 4V requires some work too.
My "dream" project right now is to mount 2 Holley/Webers on a flat-topped log. I just have to "Get around to it".
Adios, David