You're using a choke servo??! Something like a HS-85MG? Sounds workable, the way you describe it, but won't the rotation from the soft mount stress the servo?

Man, I really want to see pictures of that arrangement![8D] I've used a choke servo only once and it really is convenient to handle it with a servo... albeit with a weight penalty.

Unless there is some compelling reason, I think I will not make a hole in the motor box because without a carb stack the carb tends to spit out a bit of gas, which over time adds up. At least that's been my experience with other gassers.

Dan, the Focus motor box sticks out more than 2-1/2" from the firewall, so either you will have to modify it a bit (heh, what else is new?) to shorten it, or use the short stand-offs and make clearance in the firewall for the carb. Much easier to shorten the motor box, IMHO. For 6" (plus a smidge) prop drive washer-to-firewall, the actual stand-off measures 1-15/16". This means the stock Syssa stand-offs for 6.25" will measure very close to 2-3/16" (for the stand-offs themselves).

I'll post some pics when I actually get cranking on this.