We don't have gas lawn mowers where I live (So cal, no grass!)

But, all kidding aside, a rear-facing carb that's not that easy to see even with a mirror and pinlight, combined with zero gas engine experience, a used engine already mounted and no desire to take it off right now, I don't see any harm in double checking your assumptions and getting some opinions on how to best proceed.

So, for those you not laughing at me out loud, thank you so much for your time and points of view about where I should go with this.

I'll pay extra attention to the top end and keep an eye on if I should put a hole in the firewall. I prefer not to do that, of course, but it's now on the list.

I'm taking this project really slow, one step at a time, since it's the largest plane and engine I've owned and I'd be lying if I told you it didn't scare me a little bit right now.

I believe I have this set up correctly now in the basic sense. I confirmed what everyone has been saying about the direction the arm should be swinging. I still can't see inside very well (not as much as I can see on any given glow engine) even with a small mirror, but I believe I am fully open and closed (throttle arm as far as it can go before it starts bunching up, the middle being the estimated middle, etc all).

I'm now just waiting for my Optical Kill, and then I'll try and start it on my own and fine tune the throttle travel adjust/end points appropriatly. If needed, I'll then move on to the low and high end needle adjustment. Then (if neccessary) I will drill the hole in the firewall. The pilot who had this setup before didn't use an Optical Kill, but I want one and they seem common for every gas engine plane at my field from 50 to 150.