Bolts in the mains of the NODULAR IRON main caps of the Dart Big M Sportsman block will work fine. Save your money.
I knd of like the 4.50 4.50 combination in those. There are so many good variatiins though that are all working well for guys.
Scat dealers like Scat. Eagle dealers like Eagle. Niether are perfect but both should work for you. You might also look at the Callies Compstar products. I would use the ARP 2000 Bolt upgrade in either ones. Some prefer the L-19 upgrade.
Pay particular attention to try to match the heads, intake, and carb up for what you are using this for. Don't go too big.
Ed