If you plan on cranking the front up 2 inches I'd replace them. The stock shocks will be close to fully extended with the added height, so your ride will suffer. Basically they will max out going over bumps and such driving down the road. Those lifted shock are a bit longer fully extended and would improve the ride quality....
2002 Silverado 2500HD LB7 CCSB LT
EFI Live by Rob at ATP, Edge CTS Insight DSP 5 control, S&B CAI, PPE boost valve, Pro Fab AIH, AirDog II 165, PPE WIF sensor delete plug, 5" stainless exhaust, Cognito braces & HD tie rods, H2's 315/70 R17 BFG's
2004 Tahoe LT
2006 Silverado Z71 LS
1971 Chevy C10