Dave,
I found your webshots of the C-W dual carbs to be quite helpful with my 261 installation (Greg Hill, I hope you are reading this and look at Dave's photos at the links below).
http://good-times.webshots.com/photo/2374734500090459121DKNyTEhttp://rides.webshots.com/photo/2191350300090459121lMriBWI could not get the throttle to linkage rod thought the intake manifold (Fenton) until I installed the linkage carb-to-linkage standoffs at an angle from the carbs, rather than perpendicular to the valve cover.
http://1954advance-design.com/Web%20images/261-installation/slides/16-261-installed_5.htmlI get no back-off popping but I do not seem to get any more acceleration oomph than I got with matched dual Rochester (stock 261 engine Rochesters).
Tim