[Supras] Question about head gasket (hopefully last)

[berniek at technicaldevelop.com]

Inline 6 cylinder engines are probably the longest which use aluminum heads and iron blocks.  Other engines have shorter heads, which minimizes cumulative end to end differential expansion or head warping.  Most 7M gasket problems happen at the sixth cylinder, apparently due to cumulative differential expansion.  My JDM engine showed deep grooving in the head and block around the stock gasket crimped rings, especially at the ends, presumably from tendencies of the block and head to "walk" with respect to each other due to thermal cycling.   

I do not want to add fuel to a flame war here.  I just want to know what the consensus is regarding life to be obtained from a 7M with a Cometic gasket (mine was special ordered as 2 mm thick).  I'll be running 14 PSI boost and ARP head studs.  I'd like to be able to get 150K miles with periodic retorquing if needed.  Got that from the stock head gasket with 72 Lb-Ft. retorquing at 8 PSI.

Just out of curiousity, what did Toyota do in the 1J and 2J engines to eliminate the problem?  

Thanks.

        BernieK