A bad lifter would not cause total loss of compression which should be closer to 195 as per MB. The lifters are located on the ends of the cam followers and when collapsed add only a small amount of play.You can purchase a universal valve spring comp. from NAPA which will work fine. Some folks use and depend upon an air chuck to keep the valve from falling into the cylinder. I would strongly recommend bring the piston to TDC before starting the procedure. While you in there, replace your valve stem seal. MB has been known to use materials which prematurely harden.