Can anyone give me the exact measurment for the oil pressure line that goes thru the firewall?? The AIM on page 30,31show the hole but no measurment. Page 30 says "3"-RPO U17 .5 hole at existing dimple.I tried that & entered the cowl area.At least I used a very very small drill bit! I want to install my engine this weekend. Im adding the console guage package. 69 Z10 396-325hp any help is appreciated! Thanks