Splayed main caps on a 360?

What you should do is contact FABO member Rocket and buy a compete set of ductile iron caps from him. He has them for an exellent price.
Use those and studs and that's about as good as you can do with a Pcar block.

There isn't nearly enough materiel in the Pcar block to warrant a bolt out there. Guys do it, but it's a bad idea. That I filled pan rail isn't very strong and putting a bolt hole there, and loading it, even with 45 pounds of torque is just asking for a fracture to occur. And it usually does.