Scott, Is your Zenith a 32 with the cable operated choke lever ? The carb without the choke was used in pairs on the early Porsche 356 and didn't do well as a single unless you played with the jetting. The carb with the choke was used as a single on Porsche N (Normal) 356 engines and do well on a stock VW 1600+ . They do best mounted on a isolated port intake ( 2 tubes not one big hole). I'm not sure how easy it is to find a duel port center section that has isolated tubes anymore ,but I have seen single port isolated intake manifolds on Samba.
I ran a single port Zenith set up on my Manx years ago and it was a "no fuss" deal. I also ran one Zenith with a isolated intake center section on my 1850 stroker, 041 heads, C-35 Scat cam. This set up was a little fussier, but it did OK. I think the trick is to use a Isolated port intake. Somebody has rebuild kits in Hot-VWs for the Zenith. A bit pricey,but at least they have them. Your call, but you know how I like single port engines.
