Im looking to put my car in the low/mid 11 second range. As seen in my sig i have some things done, and im going to buy a 25% ud pulley and a ported 92/92 whenever im done building my 69' camaro (should... no WILL be ready for this season). Doing that should pick me up 3 tenths about or so ive figured out. But I have lifters, so while the heads are off i wanted to mill them and throw on some thinner gaskets. What is the minimum PTV clearence i can SAFLEY spin up to 6800-7000 rpm. I would like to take 40-50 thousanths off, but im not sure i can do that, any imput would be great.