Is there a way to limit the advance from the can? I know you can adjust the "on off point" with an allen wrench, but is there a way to limit the amount of advance?
yes, epoxy strips of feeler gauge on either side of the "notch" in the arm to limit its travel into the can but just me I think you have way too much timing being on manifold. keep us updated
Another thing you can do is to tighten the advance can spring down enough to where the beginning point is way late so that the vacuum advance is not "full on" at your cruise vacuum. Using one of those hand vacuum pumps is the easiest way to establish how much advance your combo likes. But trial and error with the allen wrench will get you there too. It will just take a bit longer to figure out.
And your mechanical advance does sound a bit much. How did you establish that as the best for your combo?
As a starting point, I use 32* mechanical advance and about 42* total with vacuum and tune from there. On the vacuum advance, I start a little low and add a couple of degrees at a time until the car starts to "surge" at cruise and then back it off until the "surge" is out of it.
