The galley plugs in the fe ford engines if drilled / removed will only allow oil pressure to hydraulic lifters--it doesn't feed the top end--the top end ( rocker shaft assemblies) is fed by a passage from the number 2 and # 4 cam bearing to a passage up to the head and then on to the rockers----

If you have the adjustable rockers, solid tappets and cam I'd suggest using them as that engine was rated at 375 hp and put out considerably more