After searching and asking all I found discussed was the 351C ARP rod bolts for a replacement.
I bought a set and measured them and it was going to take some reaming of the rod bolt holes in the rods or turning/polishing the new bolts to the correct size. The top of the shoulder was about .380.
So I bit the bullet and sent a stock bolt to ARP to see if they could match it up.
What I got was a more direct fit, readily available rod bolt.
He said the original listing is for a Studebaker engine.
Here's some pics and the part number should others need/want them.
I will add additional parts and fasteners I have selected for my new 308 when I start a complete write up on the build.
I was hoping to have it done already but it seems winter is the build season and I have been swamped with EFI conversion kit orders.
Not complaining but it really hurts my build time!
Hamilton Fuel Injection