I am no expert - I honestly don't know why anyone would want to use a 2.0 N&S instead the stocker 1.5's. Factory pipe recommends 95g springs with 1.5N&S. In my (limited) experience, that runs fine.
Going to 95g springs and 2.0's lowers the popoff - I wouldn't do that on 38's and stock arrestors.
Again, just my experience.
Additionally, I think that 75 pilots and 140 mains sounds awfully big, especially considering the low popoff.
Factory pipe recommends stock pilots and mains (70/130).
Again, if it was me, I'd go for 1.5 N&S, 95g springs, 75p, 132.5m, and tune from there. I think you'll end up right around 72.5p and 130m. I think those reeds require a bit richer jetting on the bottom?
Here's what I'd do: Put the setup together as described.
Put the boat in the water, have the engine idle against the dock. Adjust both low speed adjusters until you obtain the highest, smoothest idle. Adjust your idle screw to where you want the idle to be RPM-wise.
The take it for a ride and see how it reacts right off idle. Hesitation = lower the popoff (I think you'll be fine here)
Go 1/4 throttle for a minute, then pin it. If you got hesitation, up the pilot. If it loads up or is throaty and rich sounding, lower the pilots.
If you do change the pilots, you need to redo the low speed adjust procedure.
For the high speed jets, and high speed adjusters, follow the procedure outlined in the Mikuni manual.
(Actually, what I wrote is in there, too, but I am running out of ambition typing this up)
