Don Terrill’s Speed-Talk

I have a set of iron sbc heads I'm freshening up, got some heat cracks in the exhaust seats. No big deal, I can just put in hardened inserts other than one is cracked from seat to seat, though the thin area between the intake and exhaust. Can this be repaired with pins then still bored for the hardened seat?

Yep, put a pin through the bottom of the crack from one bowl to the other & below where the seat recess will be, then seat inserts in both seats & peen over the top of the crack in the chamber.
Got a couple running around fixed like that - making 550-600hp & getting abused hard with no issues.

Pardon the crude drawing, it's the only way I could think of describing what I was planning on doing to fix the crack. Is that somewhat you were describing?

Almost, but get the pin down lower & more horizontal - go in through the intake bowl where there is more room. It'll be on an angle, but keep it as shallow as you can.
All you gotta do is stop the crack from going further, so if you can get a pin in under it you're good to go.

I would get a bottle of Goodson fluidweld to install that pin and seat with also just to be well on the very safe side!