If it's the classic dome-topped canister filter housing, the flow restrictor should be built in. Check out the center standpipe with a bright flashlight and an inspection mirror. Somewhere near the midpoint of the standpipe there should be a small hole, about 1/16" or so. If it's there, that controls the oil flow and no other restrictor will be needed.

If you have a larger drain hole, get a main jet for a Holley carburetor, drill it out to 1/16" and thread one of the reducer fittings with a 1/4"-28 thread. Screw the main jet in, and you're good to go!
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!