I broke the Shade Tree Refugee.
I have a 1982 GL1100A that sat in a backyard in south-central Texas, under a Shade Tree, for the past 7 years, wasting away. I retrieved it, cleaned it up, freed up the engine, converted it to a single carb using a BoilerBoy manifold. I managed to get it titled and registered. I had it running with a bit of a miss, put about 30 miles on it and then disaster struck... The Exhaust valve on #4 broke off and busted a hole in the center of the #4 piston. I have removed the engine from the bike, I have the cylinder heads off, I have a replacement left cylinder head in-hand as the old one was ruined. I have a replacement piston and the special clutch socket on the way. I have the Clymer book and the 19 section Service Manual.
What is the recommended course of action from this point please?