i went 1 size up and soaked them and mine fit good. i'm a bigger guy though so you may want to get true waist size and just stretch into them if you want a tighter fit.
For my Alexeis I actually sized down 1 and left out the waist when i did the initial soak. It has stretched to my actual waist. And even after sizing down the only tighter fitting part is the waist. I prefer slimmer fits over a straight fit so I havent worn them in a few months. I might try to soak them again to get more shrinkage out of them. Im sure if i had soaked the waist it would be too tight. I would suggest getting true to size because it will shrink to smaller than your waist but will stretch back out in a few wears.
i bought a pair this spring, and sized down one. they were a looser fit than i was used to. i didnt wash or soak them for 3 months. after the 3 months of wear i gave up because i got a new pair of jeans.
I understand the fact that they are vintage straight leg, but that's what I usually wear so I'm not worried about the fit itself... The waist size was my concern, as the site states "exactly the waist size" which is way over my pant size somehow; or my tape measure is inaccurate.
Should be placing an order this week then, yay!