Heads used on 327/350/383/400 SBC engines without steam holes is Felpro #1003. All Speedmaster 23deg. SBC heads use standard 14mm. x 750" reach, 5/8 hex, gasket seat sparkplugs like NGK R5671A-7, Autolite 3924, Champion RC12YC, etc.
Chevy SBC 350 190cc 64cc Straight Aluminum Bare Cylinder Head - Series T
Chevy SBC 350 190cc 68.5cc Angle CNC Chamber Aluminum Bare Cylinder Head
Chevy SBC 350 190cc 72cc Angle CNC Chamber Aluminum Bare Cylinder Head
Chevy SBC 350 190cc 64cc Straight Aluminum Bare Cylinder Head