More about head bolts

I just noticed another eccentricity with my head bolts on the 318 poly. I believe the 62 and up poly's had 6&3/4" head bolts for the long ones thru the rockershaft. The older poly's with the 3 bolt valve covers used 6&7/8". I just discovered this while checking a number of mixed head bolts and heads. When using the older 3 bolt heads the newer, shorter, head bolts look kinda minimal as they only have 3/4" of thread below the head surface. The head gasket makes it even less. The thread depth appears to be 1" into the block with about another 1/4" of unthreaded space beyond the threads. >From what I have the longer head bolts, older style, have the grade six lines on the bolt head and the shorter ones have two concentric circles on the bolt heads.

Since these engines came originally with the .020" metal gaskets, the newer .040" composites make the bolts even a tad shorter. I am using the older style heads currently but I do have the metal gaskets. I only have 5 of the longer head bolts and I'm a tad leery of using the shorter ones. Anybody got 5 of the longer head bolts with the grade 6 lines on the head?

I'm going to double check and measure the length of the bolt chases tomorrow but I do believe I am correct.

Rich Kinsley '64 Dodge Polara 4dr 324 poly w/goodies