You can run Ls6 Springs with that. Considered buying that its a billet crane cam nice stealthy sleeper smooth idle with good mid-range. If you decide to run 1.6 rocker arms with it The following allow higher valve lift. Lt4 springs limited to .525 Lift but With normal clearance before coil bind I calculate .515" lift maximum. I'm going with 1.52 Rocker arms.
That cam with 1.6's would be .531 lift and would idle nice for the wife and get better gas mileage than a larger cam with more overlap such as the trick flow or other 223-224 Intake duration cam. It will have nice driveability but less top end power than a larger cam although mid range should be strong. That cam is billet not cast and that was a good buy you cannot buy other mfg cam with those specs for that crane billet cams run $400+ new.
These work nice with CC503's and smaller.
I bought my components individually as I could afford but a kit is better.
LT1 VALVE SPRING KIT Includes: SPRINGS, RETAINERS, LOCKS & CUPS. - Alex's Parts Sales
You will need new spring locator cups for the LT1 aluminum heads with beehive 918's Pacs or the LS6 's. LS6 springs have slightly lower seat and open pressure than the Comps or PACs.
You bought retainers
BEEHIVE VALVE SPRING RETAINERS FOR 7 DEGREE 11/32" APPLICATIONS - Alex's Parts Sales
They sell the springs and hardened cups call and tell them you need the Hardened spring cups for beehives on Lt1 heads.
BEEHIVE VALVE SPRINGS- SBC, VORTEC & LS SERIES, STOCK TO MILD - Alex's Parts Sales
CHEVY, LT1, GEN II SBC - Alex's Parts Sales
Don't sweat the torque plating here is an alternative