71 198 slant new head

So how do I get one of those bolts . I'm googling head bolt kits and rocket bolts from 75-86 heads and not seeing any sets with one different bolt in it like I need.

and can I use my rocker set I already have ? Or is it so different it's not usable and may explain my timing issues and it running like a turd . Mid June when I blew the head gasket it still ran great and sooth ( no water in oil ) I was getting exhaust pressure out of radiator . It never lost water . But it ran great on and off the trialer . And I did nothing but swap the head . I reused all old parts , lifters stayed in , push rods reused in same order , and valve train all stayed together and it all went back good obviously not that one back bolt . Any one can tell me how to buy that one bolt that be amazing .
There is no problem using your old valve train. Did you readjust the valves? Should be .010 on the intake, and .020 on the exhaust. Don't forget the valve sequence changes between cyl 3 and 4. As far as I know that bolt is not available, except as used from someone's private stock.