I'm in the process of re-doing a 235. While attempting to remove the lifters, I get them up about 3/8 of an inch, when I rotate the motor on the motor stand, with the rockers facing the floor, all the lifter drop evenly the same 3/8". Am I correct in assuming that the cam shaft must be removed and the lifters drop down towards the pan to be removed? Can the solid lifters be replaced w/hydraulic ones? If so,does the camshaft need to be changed?