Great that you got your tank coated, hopefully it will work fine for many years. As far as your intake manifold goes, I've seen that rot hole happen more than a few times through the years. What I do is cut off the egr section of the intake and I weld an aluminum plate on top of the hole eliminating any problem in the future. I have to do that with the manifold on the bench, it can't be done while it's still in the car. Then you need to weld shut the tube going to the exhaust manifold or better yet install a header like you already did. If anyone wants me to weld up their intake you'd have to send it to me. See attached pics. I do have lots of used intakes in stock so I can weld mine up and send it to you, then you send me your old one. That way your car doesn't have to be laid up for awhile. Or I could sell you an intake that is intact and doesn't have a rot hole. As far as your header goes, as long as you don't have an auto trans you're best bet on the header is using a 6 into 1, not a 6, 2, 1. I have a ceramic coated 6 into 1 header with round ports in stock hanging on the wall waiting to be sold if anybody needs one. The one in the pic is just like it except that one is alumacoated whereas the one I have hanging on the wall looks like chrome. see pic Z man of Washington