Needs a tune for a ported TB...skip rockers...they're boring. LS6 springs are pretty rough on the timing chain tensioner as well...if you want to do rockers...do 1.95 rollers and Crow 105 springs...but then that's the $500 budget alone....lame.
I'd just port the blower...open up the outlet, smooth and polish the inlet...HAI = yes. Get a tuned PCM and headers IMO...two best things...keep the stock pulley or run a 3.6"...don't get pulley envy unless you factor in an Aeroforce scan gauge or a way to tune it...
Seriously though; Buy some SSAC's or Speed Daddy's...and a DHP PCM from 3800 Performance.
As for plug wires, **** those crappy ZZP ones, get either MSD's or PRJ's. Clean the coil terminals and the ICM under them. Toss in some new AL605's, gap them at .050". I'd replace the PCV/fuel filter/change the oil/oil filter, and flush out all the old dexcrap and put in the cheap yellow or green stuff, and follow with a 180* T-Stat. Flip the upper dog bone mounts...that's free. If the lower mounts are toast, good time to replace them is when the LIM and everything is off...more room to move around. Get a solid rubber engine/trans mount in there...the non-fluid filled ones. That should tap out your $500 budget give or take a little bit.
