They make the springs from factory specifications for you. You can choose stiffer or softe
r than factory.
Plus, if you can bring the car in for installation, they will custom adjust the springs to
 make your car level.
They do vintage cars regularly. (I mean, really, how many 3 year old cars need new leaf
 springs?)

I drove my Edsel from Los Angeles to there (1000+ miles?) to have new leafs put on it,
 and if my Studebaker needed leafs, I would do it with that car too.

They will mail order you springs for you to put on yourself, if you really can't get the
 car to Portland, but the manufacture and custom installation service they do is worth
 the price.
Tell them how high you want the car to stand, and they will make it so.
Nice people, fair price, first class product.