I am moving forward using the 4.170 round bore gaskets. the cylinder bore is 4.080 so it is sandwiched between the head and block except on the top side at the 2 and 10 o'clock positions. This is how Blair set it up last time and it ran for 250 or so passes, so in the name of getting it done and it worked before, I am going to run it. Next time it is apart I will know to get 4.25 gaskets and eliminate the overhang.