Good work!!! Similar to my experience with Edelbrock heads and the B3 kit. It took a few tries to get the clearance. I didn't have to remove as much material as you.
Can you provide details on the rocker shaft studs you used? I checked around at one time but didn't find what I thought would work.
Edit: I posted the wrong link the first time
McMaster-Carr
The rockers I bought came with some, but they had a slot for a flat head and the thread lengths weren't quite right.
I wanted something that I could bottom out, and with a hex drive. These are a little long on the shaft side, the one under the breather port hits the splash guard, so you either have to remove the end of that one, or mill a hole in the guard (what I did)