The M52 and later M50 lifters are lighter, but smaller diameter so not a direct replacement. The ones I am talking about are an updated design to the OE lifters so they are direct replacement and correct diameter. Not sure which model they came out of though.
Yes cam grinds should match the lifters. A solid lifter profile will have a sharper ramp angle. You can use a hydro cam with solid lifters with a different clearance though.