aha!! who's the biggest idiot in here? That's right. You know, I was wondering why he said a Power Core silencer for his 4 stroker, but thought he's just confused. looking back i see boost (boot bottle) and his "fatty" is singular. i know, i'm being picky, but i came in thinking big bear so it made sense.
this is a case where typos will get people confused. sorry bout that jlh, i would've thought more about that rather than send you out to another place.
260 sounds like a pretty close number, depending on the temps, 270 might be good, you'll definitlely have to keep an eye as to not over lean the jetting. I've always heard one size per 1,000 feet, while that doesn't always work out perfectly, it will often get you in the ballpark. I ran 310s in mine at 1,000' (give or take), so 310 going down 5 sizes gets you at ........ drumroll .......... 260, and that's where I'd start.
Later, and sorry again for that.