I finally got the Petter AB1W on my Coronado 27 running (last owner had left it in little pieces ... final clue to making it start: valve lash is really, really critical) ...
That and a half-dozen other things
One note of warning, however: I just spotted the following comments over on the Moyer Marine forums: "Slappy Valves are Happy Valves" and "Better to have valves too loose than too tight was the reasoning. Tight valves might not fully seal and you can burn a valve as the combustion gases escape through its gaps."
I'm no authority on this particular aspect of engines. As luck would have it: All the engines I wrenched-on back in the day had hydraulic lifters