GM numbers the cylinders from the front to the back. So if you look at the back of the engine-- the driver's side head is further back, and closer to the firewall. The passenger side head is further forward. so that starts the numbers-- as #1.
The other V8s from General are different, and #1 on those, is the front on the driver's side.
Chevy 04.5 LLY, 2X, shell, XDR, MikeL Heavy duty up-grade, 6spd, TransGo, deep pan, de-badged, 65 Gallon replacement Aero tank, LBZ-mp, Kennedy pump, shimmed, Pre-fuel filter, tow mirrors, BU cam, gauges, GPS, Sirius, bags, custom grille, fender vents, HD trans cooler- Curt front hitch, footwell lights, load lights, Studs, head gaskets.