Jacob, I'm parting out a 59 model 3800, and it's got a good 4-speed. Drop me an email, and we might be able to do a little horsetrading. We're not supposed to buy and sell on this part of the forum, so let's get this discussion into private territory. My email is in my "profile", just click on my username.
Back when I had that one on the road, it would run 65 or so, with a 235 engine. If you've got the 283, it should go faster than it's safe to drive with the suspension and brakes it's got!
Jerry