http://www.compcams.com/technical/Catalogs/106-07/268.pdf
I don't see a 3/8 BBC though. It has a 1.72 ratio which is fine
Maybe you can order the 3/8 grooved balls & 3/8 nuts to go with the BBC rocker arm??
Maybe they make Chevy inline rocker arms as I did not look @ their website too long.

Try & give them a call & see if they can help you.
Tech Support: 1-800-999-0853
BBC will work w/a 3/8 stud.


MBHD

12 port SDS EFI