Back in the 60's Chevrolet made a head bolt with a hold in the center so as to oil the rocker arms. Do they still make such a bolt and what is the part number? Thanks

The hollow head bolt was part # 3764578. It was required when a 1959 or later head was installed on a 1955-58 engine. It reduced to full pressure oiling to the rocker arms to restricted flow.
We also used to put them in some engines when the oil passage between the bolck and head would get plugged-up.
The 1959 and up rocker arms required more oil pressure because the grove inside the rocker arm was off-set to one side .

Thanks Gene I used to work at a Chevy garage when I was young and remember selling these bolts.

I remember selling the bolts but don't remember being young

Well, let me tell you ...I remember .... aw nuts, well I thought I remembered.