Casting number 3836848 was used for the high compression head on the USA 235 engine beginning in mid-year 1957, I believe. The Canadian passenger car 261s also used the 848 head, possibly modified with six extra coolant holes to facilitate better cooling of the siamese-cast cylinder pairs. With the extra displacement of the 261, an 848 head would make it a real performer. A couple of those lifters show a hydraulic plunger bottomed out due to the valve being open with tension on the spring, which also strongly suggests you've got a 261 passenger car engine with a hydraulic cam.
Jerry
