I understood what you meant. If your wave washer puts too much pressure on the shift lever, you would want to put a shim on the threaded section of the shoulder bolt (that is the same OD as the shank or smaller) to effectively make the shoulder bolt longer and reduce that pressure. I would do that before I just left the shoulder bolt loose.
But if all of the parts are clean and not damaged or distorted, the shoulder bolt should be tightened fully (albeit torqued lightly) in it's threaded hole, and the wave washer should not bind the lever from pivoting, just restrain it from rattling / moving laterally on the shaft.