Yeah I got a 7" lower with a 2.875" upper, if I go to 3.25" upper or a 6.5" lower that's put me about 2.09:1 to 2.15:1. And with my supper chiller boost reduction, I think I'd lucky to make 5lbs with that set up.

P.S. I'm looking for a automotive style keyed front shaft if someone has one laying around ( Blower is apart rebuilt and waiting to go back together :).

They may have been 3.5" and 7" stock. I can't remember for sure, and thinking back, I think they were.
Either way, you are more than 2.15 overdriven.
Divide bottom diameter by top diameter and you are at 2.43:1

i believe eve there were 2 different ratio / pulley combos a standard and a high altitude

The high altitude was supposedly just a smaller upper pulley.
I've heard Merc had them but never seen it listed in any parts lists.

Ok doing the alighn-hone and need to know what main cap bolts to run, stock or ARP?

What's the max HP stock GM 4-bolt main bolts should be ran up to with a blower?

Thanks

for the price of them...I would run arp...that's what I'm doing with mine...went with the bolts instead of the studs...extra insurance never hurts imo

Ok need to figure out windage tray options.

​​​​​​I plan on getting a "offshore" style 8 to 10qt oil pan, is it better to run a oem style windage tray bolted to the main caps or get a pan with a windage tray in it and eliminate the oem style one?

You don't need anything more than the stock setup.

"Stock set up" is good to how much HP?

Stock are 8qt pans and should be fine to 650-700 as long as you have a good oil cooler.
Same pan is used on the 700sci
Genuine Mercury & Mercruiser parts. 845668T PAN ASSY-OIL Genuine OEM Mercury Marine-Mercruiser part