Ok what is pinning,the hoal is not wisibal in the foto
They make tapered cast iron pins. You drill a hole at each end of a crack, or if the hole is small enough you get the hole to size and screw the pin in until it breaks off.
Then you drill another hole that is half way through the pin you just installed, so the pins overlap. Install the second pin and keep installing pins until the crack or small hole is sealed up.
The pins are pretty successful IF you can get them in the repair. Then you can add some stop leak to the cooling system to make sure you don’t have any little leaks.
Here is some free advice, and it’s worth much less than you are paying for it.
The exhaust port and valve in these heads is way too big to start with. So we’re I don’t the your heads, I’d get the best valve job I could squeeze in there, roll the short turn as best as I could and then I’d put the grinder down and walk away.
The port will flow more the bigger you are it, and it will also start killing power very quickly. Porting an exhaust and using flow numbers to determine of the port is getting better is the worst way to do it.
You want the exhaust port as small, as fast and as quiet as you can get it, and ignore the flow numbers.
That’s just my opinion.
