I didn't see it was a 12 to 1 motor. Do as newbomb said on the plugs and don't be cheap on the fuel also. It's gonna cause a lot of damage if you are trying to use pump gas. I've got one car with a 12 to 1 with iron heads 340 and I pay for the 110 race fuel. And you can mix it up some. If you...
Well they lied to you. They used to sell n12y, n11y, n10y and n9y. Now they don;t sell the inbetween ones. So n11y would be one heat range colder. I've run all of the above in my 340's without issues although in the hotter motors I used n10 or n9. In my Hemi it was n63y's.
Snap on also has a plant in the same city as Tri-city. They closed it and moved it then brought it back. By the way what were the costs to have the work done?