So glad you got underway on that carb linkage. I saw that extender bit and was about to ask about it.
It seems to be a type4/DTM shroud issue. Lenny's linkage(DTM/type4) had the extensions both on the carb base and on the throttle levers. The spacers move the bar backward, to avoid interference with the shroud.
I don't like the way it looks but it seems to work.
CB Performance supplies one spacer to fix the offset on type1 linkages as well.
I know it would be near impossible to install and adjust, but is it possible to install the linkage reversed? That's how mine is on my Spyder, but I'm lucky enough to have a 911 shroud that actually isn't in the way.