1967 Chevy Chevelle Oil temperature?

It probably would not heat the oil enough to notice. You have a couple of things you can do to make you feel better, and gain a little clearance. Mark where the header is really close to the filter housing, take it off, and gently ding it in a little to gain some room. You should also go down to your local speed shop or parts house and by a conversion kit to go from the canister type filter to the spin on style like on the newer engines. Mickey-d