chevy didn't come ouy with vortec heads until the 90's . I'm thinking about 96, so just because they are centerbolt head doesn't mean they are vortec. sorry pal
5,700 cc
4300cc 1 Liter=100 cubic centimeters
stock 350 heads are 72 or 74 cc
58.cc low torque swirl chamber head
53
I was unable to find that exact number at mortec.com, however if you have a set of 3991492's, they are very possibly a set of 70-up LT1 camel hump heads with 64 cc chambers. These would be valuable heads.
CC Vest was created in 1989.
62 up 327 300 hp and higher had "camel hump" heads. these have 64 cc combustion chambers for 10.5 compression on a 327.
53 cc lt1 heads...92-93 good heads for porting
I have the same heads and from the info I found they 76cc heads with 1.72 intake valves
54cc
Thay are all different. Need the year and cylinder head casting # It could be 60cc.65cc,70cc it could be anything. Ask your question again with this info. 1989 Chevy 350 t.b.i I still need the casting numbers that are under the valve cover. They will be stamped in the head were the rocker arms are. Most of the heads for that year were 64cc. but need casting # to make sure.