Once the magneto proved to be just a piece of the whole problem, I decided to restore all parts that could be the cause. I started with the head and manifold, and then the carburetor and spark plugs.
The head needed 4 new value guides, 2 new exhaust values, cleaning and resurfacing. The head was done by Lloyd's Cylinder Head Repair in Rogers, MN.
The Restoration of Glen Westphal's Waterloo Boy