REMFLEX EXHAUST GASKETS Graphite Pontiac V8 Header Gasket 2 pc P/N 12-002 see link below
https://www.ebay.com/itm/REMFLEX-EXH...EAAOSwCH9eHBEd
They cost a little bit more, around 35-36 bucks, but they seal great. Put them on stock round port manifolds 4 years ago and haven't had any trouble yet. I have A/C so the passenger side is a bit trickier and also had to notch the gasket to clear the dipstick tube. If you have headers it's easier. If you try these, remember...They are graphite impregnated, so the coating is brittle, be careful not to bend them too much, or they will crack ruining the gasket. They do flex but are unforgiving if you bend them too far. good luck