-8A Engine Control Cable Routing

[pvalovich]

I hope to hang the engine this weekend, so want to punch as many firewall holes as I can before mounting. All was going well IAW Vans Firewall Forward instructions til I got to the engine control cables, where I was referenced to Drawing 21. There, I observed a serious caution about making pecise measurements using coat hanger wire forward, and "Typical" locations for the holes. Anyone have words regarding their experience? Is this one of those "TLAR" (That Looks About Right) measurements, or do I have to get it to a gnat's a**? If the latter, what is that?

I have an Aerosport IO-360 horizantal induction engine and a Vans delux RV-8 throttle quandrant.