I agree some of the unshrouding on those must be for a big bore motor. I scribe a line around the head gasket that matches the stock bore then put the head on a rotary table and with a ball end mill go to the gasket line. One of the nice things of these heads is that the short side is against the cylinder wall so the shrouding does not have as much of an effect as the short side as it does in a car because the short side moves less air around the valve as the long side does.
Today I added a timing tape to the flywheel installed and set up my degree wheel to fine TDC and degree in the cam. I am going to try a genuine Honda coil. I have read these have less high rpm retard but have no idea if it is really true. The coil is much smaller than the stock coil and maybe it has less inductance than the stock coil so maybe that is why they retard less, but I would expect less spark energy. We shall see, I am also using a non resistor plug cap. The cam degreed in about a degree and a half advanced so that if fine for me. I also checked total duration so I have input to pipe max to calculate exhaust length.
I also added a neo bar magnet to one of the drain plugs got that tio from a OldMiniBikes member a while ago.