OK, are you kidding or are you serious about 45 degrees being good. I always thought if it was off the tab then something is wrong but I am a believer if it runs good then don't screw with it.
No, I am serious. They usually run fine at 45, at idle. Depends how hot it is. And sometimes they don't like to start with that much advance. You wouldn't want to be at 45 under load, might detonate.
As for staying on the tab,,,,,,have you ever revved your engine while looking at the timing? It goes way off the tab. Edit: tabs only go to like 12 or 14btc, and that's where the damthings are just beginning to run right.
I run a locked out distributor(not recommending this to you, just making you aware such a critter exists) on my car. Timing is at 38° starting, idling, and full load. That would be real close to vertical.
I also have a zz4 that I don't use vac advance on because I think vacuum hoses look like *** and the engine doesn't need it anyway, just centrifugal advance. I have it about 20something at idle and 30something at speed. Not recommending that to you either, just making you aware there's more ways to play.