Be sure you indeed have a '57 235. The lifters for that year only are different than the '55-'62 lifters. There is a date code on the block above the starter. It will have a letter followed by some numbers. For example F 14 7. Would translate into June 14, 1957. The same number is on the inside of the block wall near the crankshaft. You'll have to remove the oil pan to see that code.
That head you have "848" is the good one. Made '58-'62. Remove the valve cover to see the date code on the top of the head. That code translates similar to the block date code.
