Any 5.7 ,350 roller tip rocker will work. Look on ebay. they have them for $69. Also try Summit and Jegs .
Try Comp Cams magnum roller tip rockers. Or something from Crane.
Remmember that wheel size plays a important part in the final drive ratio! If you have large tires with a large outside diameter . You can effectively negate your 410 gears. great for rock crawling . Really really bad for performance. If speed off the line is what you are after.
Do Not, I repeat, Do not! Use anything that will block your intake! No spiral charger! As said before in the first post , will do absolutely nothing but block air flow. Now if you can figure out how to put in 6 of these right before the valves inside of the heads. Then you are in business. As stupid as that sounds.
Chevy vortec heads are great! they only need help on the exhaust side. They are a great upgrade for any pre vortec engine. Chevy did a great job with these.
TPI engines will love that spacer between the throttle body and the intake, they make several throttle bodies with porting and bigger injectors for this engine. Try Edlebrock , Only problem is cost. the other only 2 injectors! Check Edlebrock and look at their new intakes for the tpi. Instant HP Gains!