The breather valve seems to be a little off
Don't worry about small amounts. Most of them will not center exactly. It's irrelevant in a street engine. If it's a tooth out, then fix it.
Piston position indicators are accurate enough. You can use a pencil and get close enough. But the screw in dial indicators are much easier and more accurate. If your really keen you'll put a timing light on it afterwards anyway.
There is about 30 degrees of movement in the advance/retard system.
But normally, if the mounting nuts are too loose. the mag wants to go full advanced.
Something isn't adding up here.
If you have it fixed at 45 BTDC and your telling me it becomes 30 degrees too far advanced after one ride ......
The engine wouldn't be running as you pulled into your driveway. These things won't handle 75 degrees of advance.
How are you checking the timing after the ride ?