SS/JA - What heads are legal?

[K Stubbs]

"292" – 3917292, or 340292. Both are good performance heads. The 3917292 was
found on 1968 327 and 350 engines, had 1.94/1.50" valves, 64CC combustion
chambers, straight plug configuration, not sure on the accessory holes, and I do not
have any port volume data on these heads. These heads have double hump casting
marks. The 340292 was available from GM "over the counter". This version had angle
plug configuration, 2.02/1.60" valves, 64CC combustion chambers. These were known
as the "Turbo" heads.

The 292 casting is listed as an accepted head on this combo. They are not referring to the over the counter head, there were two different 292 heads.