[PontGuy]

Now you are heading in the right direction.

I've adjusted the APT on my Lemans carb as much as 1-1/2 turns richer from where Cliff had it set and per my wideband this resulted in less than 1.0 richer cruise A/F ratio. So don't be afraid to turn it. But record the changes you make so you can always go back. FWIW After a few thousand miles and tuning to get everything optimized I ended up with APT set exactly where it started.

A bit embarrassed that I assumed the head cc numbers were correct in calculating CR. At least I wasn't alone.

So at the end of the day your setup is not all that much different than the engine in my TA with the XE 268 (except you have the nicely ported heads). My seat timing is even shorter than yours and tuning has been pretty tricky but it is running pretty good now. As mentioned I have a 10 degree vacuum can on that engine. More than that would be asking for trouble. Yes it still tends to run a bit hotter than I like, and yes the oil pressure is lower than I like when it gets over 200 deg during a long hard run in hot weather. Sound familiar?

If the engine won't crank with more than 13 deg initial and the engine wants more timing then suggest you invest in a mini-starter, or get the distributor reworked to bring in more mechanical timing. Trying to add timing with too much vacuum advance isn't the way to go.