Cam specs are not universal. One cam grinder cam use a different point on the cam lobe to get his/her advertised specs. Some measure advertised duration at tappet lift (hydraulic or solid) while other measure at valve lift, ie .006" lift at the tappet is .009" at the valve. Nothing you listed is enough to make any difference.
Factory SAE specs for the 4-speed HO "068" cam is Intake Lift @ zero lash - .414" +/- .011
Exhaust Lift @ zero lash - ..413" +/- .011" Int.Opens BTC @31, Int.Closes ABC @77, Int.Duration 288, Ex Opens BBC @ 90, Ex Closes ATC @ 32, Ex Duration 302, Overlap 63.
The outer valve springs are the same for both the intake/exhaust 63.3-69.3 lbs @ 1.5613" measured height - valves closed, 132.7-142.7 lbs @ 1.1473" measure height - valves open.
Inner springs show a slight difference for the open measured height for intake/exhaust 54.7-59.7 lbs @ 1.5213" measured height - valves closed, 118.6-128.6 lbs @ 1.073" measure height -intake valve open and 1.083" - exhaust valve open. (.010" difference noted, but unknown as to why. Possibly the seat cut in the head for the exhaust valve or the difference between the 30 degree seat of the intake valve and 45 degree seat of the exhaust valve.)
In Jim Hand's Pontiac book, he states that the Lobe Separation Angle (LSA) is 116 with the Intake Centerline (IC) being 113. LSA is the distance in cam degrees between the intake lobe center and exhaust lobe center. IC is the peak lift point of the intake lobe as measured in crankshaft degrees. The intake and exhaust may not always have the same peak lift point due to unsymmetrical lobe designs of the cam.