Since you've already done the intake and even P&P'd the lower, I'd recommend keep going with the engine build. You'd basically just be P&Ping the upper intake and then diving into the engine... And the supercharger would take the place of the CAI you already spent $$ on.

The high mileage and new exhaust are additional reasons.
Supercharging is nice, also (talked to a few guys at car shows who have them) - major upgrade, but still just a bolt-on; and since you won't always be in boost (with the centrifugal styled Procharger), your mpg shouldn't suffer too much either.
The choice is yours.

But if you are set on building it N/A, I would recommend talking to the guys at SSM (
www.supersixmotorsports.com) -- they know a
lot about our sixxers.

__________________
YELLOW JACKET = 1998 Chrome Yellow V6
POWER: BBK CAI, TB, UDPs; Bosch Platinum +4 plugs
BEAUTY: black projector headlights, taillights, and mesh grille; 5% tint; shorty antenna; interior billet
ROLLERS: XXR 006 black spoke with blue lip; 18x8.5 & 9.5; BFG KDW/2 245/40R18 & 275/35R18
DRIVER: Jonathan, 6'2, 190 lbs
RIDER: my wife, 5'4 brunette hottie

and my 1st baby on the way...
