12 port heads (6 intakes on the driver's side, 6 exhausts on the passenger's side) were a Southern California hot rod thing in the very early 1950's. The first were cast by Wayne Horning for Chevy, followed shortly with heads for GMC engines.
If you'd like the early history, seek out "The 12 Port Story" written by Herbert Hall, a series of 9 articles in "The 12 Port News" in 1981-2.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
