They all have belt grooves and they are all interchangeable as far as balance. All slant six engines are internally balanced. The only differences I am aware of is they have different timing mark locations from early to late for example, but I don't know where that split is.
Are there other options which fit the crank snout that could be modified. I am really trying to find one with a smaller OD which is my primary goal.
That is my second option and something I have thought about. Mainly as I do own a lathe. I recall the 170 having a smaller OD, but can not seem to find a supplier which sells them new as a starting point.
I am doing some research for a project I am going to tackle based on the outcome of this question. I may end up buying a Grizzly Mill for XMass this holiday season as a result :)