Other than the broken bolts it's a piece of cake. Lower head bolts are the toughest.
Get your self some 80 grit sandpaper, something dead flat and do figure 8 patterns on the sheet with the head. Takes me about 40 minutes to an hour to complete a head grind.
Yea, that's exactly how the service manual describes how to do it, I've done this process countless times on vehicle heads and other small engines.
One of the bottom head bolts snapped off, one in the middle snapped off, and the one on the stbd side that has the back sides of the threads exposed ripped the threads out of the block
I spent 20 minutes with a torch heating that one and squirting pb blaster in it, too. Sometimes there's nothing you can do and it's just gonna happen. This engine has a bad case of corrosion. But the cylinders have no scoring and it has ~130psi, so it's worth the effort.
