No, a 1998 Chevy Silverado does not have a proportioning valve that requires resetting after replacing a hard brake line. Proportioning valves on vehicles of that era are generally passive; they don't have any electronically controlled or manually adjustable components that need resetting. The valve's function is entirely mechanical based on fluid pressure.
While you should bleed the brakes thoroughly after replacing a brake line to remove any air introduced into the system, there's no separate adjustment or reset procedure for the proportioning valve itself.
