After using a buddy's Matco timing light this weekend, it gave the same reading as my old Craftsman. Apparently this little 340 just likes a TON of initial ignition timing - I ended up with 30* initial.
If you are using an aftermarket box of a Chrysler module the timing retards with RPM. You can't see it with a timing light, but it happens. As much as 2 degrees per 1000 RPM.
I've never lost sleep over a timing number that seems high to everyone else. Most guys don't test. They only do what others have told them.
If your stuff runs better with 30 degrees initial with your timing light, do it. Unless it's hurting parts.