I just finished changing the cam in my 54 mod. 235. Hot Rod is correct check and make sure there is an oil gallery at the lifters.(some blocks were designed for solid lifters and the oil gallery was not used)and use the proper (new)lifters for the cam used. It is nessary to remove the grill and radiator to get the cam out. You will also need to remove the oil pan to get to the bottom bolts on the timeing gear cover. This is not a hard job just time consuming.
Good luck

1953 Chevolet 5 window