You have a Vortec 454. Fairly nice engine, IMO.

Delco 41-933 plugs. Don't bother with 'alternatives'.

15W40 oil. Or ideally a 5W40HD oil like Rotella Synthetic or Citgard Syndurance. Citgo now also has a 0W30 Syndurance for very cold weather operation. I'd... Login to read more.