Lockup to non-lockup question(s)

So I'm reviving this thread as it seems my converter/rear gears future upgrade has kinda snowballed. I don't like the thoughts of hwy driving at 3-3500 rpm, so it makes sense to use a converter that would work in an OD transmission.
I want to use one with as little mods as possible.
What to use and which vehicles did they come in? There's quite a few wrecking yards around here.
Thanks