Dusky

Yeah, isn't that called a 'sniff tester' or something like that?
Haven't found these in Belgium ( yet).

Tbh, my biggest concern of the hydrolocking would be that the cylinder bores would rust.
Looking foreward to replacing the HG! Any small things that I could do while i'm at it?
Going to lap the valves for sure, new air filter etc,..

88 orangepeel notch

Have the heads checked for flatness, I'm assuming they're the stock cast iron heads, not aluminum aftermarket. Cast iron heads won't warp like aluminum so you should be OK. Other than that, slap her back together and enjoy.

Of course there's always the option of modding since it's apart. Cam, intake, better heads, etc, but it's a slippery slope. Once you start, it's hard to stop lol.