I spent some time looking in junk yards for electronic ignition advance plates and found a factory 11° plate in a motor home distributor. This was gold to me as I don't have a welder. I am setting up my 340 with 12° initial advance and get 22° crank degrees advance from the distributor for a total of 34° total mechanical advance.
DDG has some videos on this topic as well: and
But there are many more.