You can shrink them in the washer/dryer. Wash them for a long cycle in the hottest water you machine has.
Then put them in the dryer for a long time while they are still wet on the hottest setting.
You can do this a few times.
With the fabric still sopping wet and you put them in the dryer, the steam and heat will shrink them.
They look pretty good for a 1978 look 
they dont have the chest pocket flap, but you could do that
if you or your mom/gf has a sewing machine or can sew by hand
