360 build-need help.

ok, now I'm really confused:) I thought I had an 89 block but it looks like a 92 by the block stamp. My stamp is 53006921-360 or is the 92 in the stamp not the date code and only part of the ID?

1989-92 360
5.9
4.00
V-8 Roller Tappets

As far as cams go I was looking at maybe this one. Why does it say springs required? Will I need to change mine if the cam does not exceed my springs max lift?

COMP Cams
Manufacturer's Part Number
20-745-9
COMP Cams Xtreme Energy Camshafts
Summit Racing Part Number
CCA-20-745-
Hydraulic roller tappet
Basic Operating RPM Range
1,000-5,000
Intake Duration at 050 inch Lift
212
Exhaust Duration at 050 inch Lift
218
Duration at 050 inch Lift
212 int./218 exh.
Advertised Intake Duration
264
Advertised Exhaust Duration
270
Advertised Duration
264 int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio
0.480 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio
.480 in.
Valve Lift with Factory Rocker Arm Ratio

0.480 int./0.480 exh.
Lobe Separation (degrees)
114
Computer-Controlled Compatible
Yes
Grind Number
CRS XR 264R-12
Valve Springs Required
Yes