SoCal, to answer your questions:
"Would I have to get the Edelbrock Performer RPM w/1996 Gen-1 heads {$175}or would I need just the Performer RPM (non-EGR){$117}?"
---You need the Gen-1 manifold. You also need the new style intake gaskets. You must purchase these through a dealership and they run around $26 (mine were anyway). We have the RPM Gen-1. There may be another alternative to this as well. The new issue of Hot Rod just came out and they build a bucks-down motor and did some grinding on a Weiand to make it fit okay. The heads can be drilled to accept the old style manifold bolt pattern if you so choose. I'd have to really look at that article though to see what it was they did to that manifold. That'd also save a couple bucks on intake gaskets if you did the redrill job yourself.
"Also, I would love to have Trick Flow(made by Summit) or Edelbrock heads, but I don't have the $1000 to fork out. I shouldn't need to get to the 4000 RPM range because this will be a daily driver."
---Do a search on Vortec. Someone mentioned an article that was written stating the Vortecs outflowed or flowed as good as the above aftermarket heads up to 6500RPM. Right up your alley.
"Also who makes centerbolt valve covers besides GM? I've heard Moroso made some, but they're expensive."
---Summit has chrome ones for $40 or $50. You also need to buy the gaskets for these from the dealer plus the bolts. I bought some junkyard ones for $20 and my brother painted them Chev orange. Very cool looking.
Additions:
---Yeah you need to run the self-aligning rockers (in the HR story they got them for $50) OR, contrary to what 73Malibu says, you can run guideplates. We had them installed. We are using roller tip rockers with them. If you are keeping the RPMs down and are not running more than .450 or so lift cam, then these will suit your purpose very well and be very cheap since you can pretty much run them out of the box without changing springs or doing any machine work. Scoggin Dickey Chevrolet in Lubbock, Texas has them. (
www.scoggindickey.com, I believe is the address.) Call some places around you and tell them you can get them for $400 and see what they tell you. I had dealers offer them to me for around $430 or $450. Lots cheaper than $1K.
If you do that search on Vortec there was someone who responded to one of my questions with a very detailed explanation of what it takes to use these heads. I can't think who helped out offhand, but it was great info.