WOT Range for a 96 90hp Crossflow is 4500-5500. The 90 makes its Peak Hp at about 4700-4800rpm
Isn't there a Sticker on the Airbox that states WOT Timing?
28 BTDC was common on the 90hp. However, setting that at cranking speeds could yield a different value when running at High Rpm due to the Characteristic of some Electronic Ignition Systems. Best to wait for the Factory Manual
As for the Joe Reeves Method... I prefer the Factory Method. so wait for the Factory Manual, it is only 2 weeks away
A 0.030" Overbore, isn't going to affect anything. I doubt that adds up to extra 2 cubic inches, might give an extra 1/2 hp,