I have the same vintage trailer and had the same problem with the bent
hitch. I took it off. Took a piece of 2" square tube, sleeved it over
the end of the round tube on the trailer, drilled two holes and bolted
it together. Then placed a standard US 2" trailer hitch (from Harbor
Freight) over the square tube and I can't remember if I welded that on
or bolted it. Tows a lot better with a straight hitch!

I have the original surge brakes which work. There is a bump when you
accelerate when the braking mechanism decompresses to release the
brake. I'm guessing you can make an adjustment to reduce the amount of
movement but mine doesn't bother me that much.

I'll take a couple of pics of the hitch next time I am at the field if
that will help. Allan.