Welcome to the Dark Side!
Still have the stock cam? If so, it's a flat tappet cam, so ZDDPlus is basically a requirement. If you're not sure, use it anyway until you're able to figure it out. I think you can get it from several of the vendors on the board here. For sure Kirban Performance sells it. I would bet that Full Throttle Speed does, Arizona GN, TR Custom Parts, G-Body Parts. There's got to be several of them.
Use a quality filter. AC Delco used to be THE filter to use, but I don't think so any more. Can't go wrong with a Napa Gold or Wix! I'm sure there are more.
As far as oil goes, use something reputable - no grocery store brands!!! Lots of guys here will spend the extra cash on Brad Penn, Joe Gibbs, or other supreme quality oils, especially if they have a high-dollar build. I use Castrol. I'm pretty sure I've determined by my research here that using a synthetic oil is not only useless, but may be counter-productive. If I were going to use a synthetic, I'd use Royal Purple.
Post your modifications in your signature once you get them all figured out. You're in a great community here; most people are more than willing to help. Try to locate some of the boardmembers around you so that you can pick their brains for ideas & tips until you have your wits about you with these cars. They are REALLY fun, but can be a major PAIN also!! I feel like I've been lucky.
We have a great bunch of supporting vendors on the board. Please support them as much as you can!!
For some great reading, go to
www.vortex-buicks.com. I've read pretty much the entire site several times and constantly refer to it for tips & tricks. Another is
www.gnttype.org. A wealth of information between these two sites and this board.