Should I get a hydraulic roller lifter or mechanical roller lifter kit for my 4x4 truck?

I went to NAPA yesterday for a rear main seal for my 95' Z71. The guy asked me if I wanted another one. I asked what was wrong with it and he informed me that it didn't have a title and has a collapsed lifter. I didn't ask how many miles it has but he only wants $500 for it. I can probably get another truck like it from an auto salvage and get a salvage title for that one and use the title for the one that needs the lifter. I've got enough mechanical ability and a 'Haynes' repair manual for the truck but it doesn't have instructions for the lifters. I looked under the valve train section and there isn't anything there either. Any advice?