Brimson you are the GOAT man, always willing to throw out knowledge to help a brother or sister out. I’ve been feeling “tippy” with my last egg shaped deck I bought and was curious if they all feel that way.
Ha yeah - it is skateboarding, so I am happy when I can help people, more than anything else.
As to the board being or feeling tippy, I notice that a lot more on a board that sits wider than the trucks, but it can also be just down to overall truck size, so when I am on 8.5" wide / 149s and up, everything feels much more stable, than when I am on 8.25" wide / 144 or below, on similar size boards, so for that one you asked about, I think 8.5 trucks would work well.
I was very stable on the 8.12 deck on 144s when they came out, but a lot of people don't want to have trucks wider than the board, hence going down a size, especially on egg shaped boards, where the trucks tend to stick out or are way more noticeable as the board tapers towards the kicks.
Some boards you just have to try either and see what works best though, so I guess if you had trucks of either size already, it wouldn't be such a big deal, but if you were putting a board together from new and needed to order parts, then it can get a little more tricky.
Hope that helps anyway!