HEI conversion time...

I didn't even use a sink on mine. Someone on my 67 had already drilled a couple of holes up under and on pass side of wiper, which is a flat area of the firewall. One of the screws they used to mount the old ECU was small, so I used it to mount the HEI, and drilled one more hole. I used thermal grease, of course. So far, two hot summers has not let me down. I do carry a spare.