Looks like a good project to me! Welcome!
Too bad you're so far away, Nordies got a pretty smokin deal on some C9 heads up in Vegas that has been haunting me a bit. That'd cure your compression problems and probably a lot of flow issues as well. Be a lot cheaper that way to use stock style forged vs flattops or domes to get the compression up.
As far as the Vac secondary deal, I think you're perfectly fine with it. Everyone else disagrees with me, but I have yet to see anyone illustrate a real difference on a lake/river pleasure boat, unless racing the things. (Which a lot of us do, informally and formally, don't get me wrong!)
Good Luck! We're here to help, and confuse sometimes,......

Ray