I've been there before several times with this problem. While Ken's solution is the quick'n'dirty answer, it does allow some slop into the system.

The problem with having the carb up against the the firewall is that, due to the "up and down" travel of the throttle arm (caused by the rotary, instead of linear, movement), you need a pretty good sized hole for the pushrod to be able to move in that vertical plane- while it is pulling and pushing- without binding. Note that the "vertical plane" I mentioned is perpendicular to the axis of the pushrod movement.

IMO, the best solution is to take the time to fabricate a mechanical linkage. The afore-mentioned DuBro kit is good, but you can make one out of stuff in your junk box. Basically, what you've got to do is to arrange the throttle arm to be moved from the FRONT side of the firewall. The Dubro kit bolts to the engine mount and is pretty fool-proof. See next post for a home-made job.

This is on an OS 1.08, but the principal is the same.