[rotorwrench]

For clarity, the Snyder's main bearing bolt kits are grade 8, in lengths to fit both the two forward caps and the rear main cap. They use what appears to be lock-o-seal washers to prevent seepage on top with plain washers under the heads. The nuts are a high profile plain type nut.

I've had similar problems on the Lycoming aircraft engine con rod cap bolt hardware. I had to taper a socket to clear the edges of the cap where they are spot faced. The spot face diameter is not a very large diameter so it interferes with the tool used. The socket used was a standard height Snap On socket. These sockets are about as thin as they get but still too thick. I tried using cheaper sockets but they always cracked under torque. The particular rod bolt I'm referring to, are stretch torqued to proper length so they are tight. No need for a locking feature which is rare in aviation but they have special nuts too.

Original cap bolts are likely out there but a person may not be able to purchase just the bolts. It just depends on who has all the old model A motors laying around for parts.