Valve springs are important. I would toss the OEM springs and go for a set of early gm 327 springs and retainers. it is easyer to do it now. I have had the stock trooper springs brake and get so weak that they mushroom the end of the valve stem from bounsing on it. I get them on EBay.
http://cgi.ebay.com/ebaymotors/550-...ategoryZ33621QQihZ008QQitemZ180080936882
they closely match the 3.4l HP springs.
While your in there replace the valve stem seals with vitrons, intake and exhaust. Fel-Pro or GM will work.
After doing all this right the first time you may never have the pleasure of removing the valve covers again.

John in LV

3 90 Trooper V-6's, 5 speed, 4.3L TBI, 31" BFG AT's, Fender Flairs, Bored intake, 1.6 roller rockers, MSD Coil, Jacobs Omni ignition. Heavy duty torsion bars, Rancho 9000 Shocks CAN'T SPELL, TO OLD TO LEARN, GOD BLESS YOU IF YOU CAN.