Nice... From what I have found, the countersunk cam retainer plate is only required with VVT, Michigan motorsports has the cam retainer plate with ARP bolts for $40.

Cam Retainer Plate

 

I use non-countersunk bolts on the countersunk retainer plate with no issues. I use allen head bolts, not sure if they are ARP or not.

 

That is not true!

I recently assembled a Non VVT Gen3 engine with an aftermarket LS2 Style timing set that did not clear the ARP Bolts. I had to remove it and install a countersunk plate with bolts.

 

I'm sure it will work, for a while. I wish you well on doing that with no long term reliability issues. By having point to point contact you're putiing tremendous force on a thin cross section of hardened plate steel. When GM first changed to the flat head design, Kurt Urban told me not to torque the correct flat head screws to the factory spec because they were seeing plates crack occasionally. This would result in a measurable drop in oil pressure. Personally, I'd never do that. As always, YMMV