you will sometimes hear references to a "Buick head" for the SBC.
this is a race head which adapted the racing Buick v6 combustion chamber and porting to the SBC style layout. it does NOT fit on any Buick block.
the Buick 350 was the last revision of the SBB design and they flopped the intake and exhaust valve orders from the earlier engines so you CANNOT use earlier style heads ( 215, 300, 340, Rover ) on the Buick 350.
TA Performance has a Buick 350 head and single plane intake coming, but they are not yet in production.