Need help decoding engine vin

[My74gto400]

Recently bought a 74 gto that had a 400 put in it by previous owner. Trying ti find specs and info about this engine. Here is what i found out so far. Engine vin is 26N698293. I know that 2 = Pontiac, 6 = 1976, and i think N = Norwood plant. I also found the engine code, 0521378. XS. I also know that the 74 gto only came with the 350 and that my gto had a 3 speed manual trans In it from factory.
anyone know where i can find more info about this?
thanks

 

[92 Sunbird LE]

XS = 170 HP 400 , 310 TQ, 7.6 to 1 compression , 2 bbl carb , late built 1976

About 260 gross HP by pre 1970 readings.

Head casting #s? ( 2 letters)

Doug in P.R.

 

[cammerjeff]

Head casting should be 6X if it has the stock heads on it. Another thing thing is the late non TA 6.6 400's do not use a harmonic balancer just a hub to mount the crank shaft pulley, and to seal on the front main oil seal.