I think it's ok too. Not even letters-matching..lol. I bought the Bird from a Ford Dealership 3 months ago that told me it was an H.O. with matching numbers. But it does have a superb period-correct setup and original matching TH350. Hey, is it common on these V8 heads to get hotter in the middle two ports? Fresh paint changed there first. might be cause they're 400 heads on a 350. I stuck a camera up engine when i replaced pan gasket. It's got ARP rod bolts (which is good) but i cant figure out the pistons. I attached a pic of the inside and top of piston.