There ae several ways to do this. How much do you want to spend in time and
money? When I got my 85 westy, it has so many leaks in the coolant pipes,
it looked like a water fountian. This , without the radiator cap installed.
I freaked out.Could it even be repaired?What I did was to get the
fiberglass pipes from a 86, 2.1. They didnt fit too good,but a top radiater
hose from a 88 Mazda 626 4 cyl completed the job ok. I use it today.

It turns out that only one of the two coolant pipes are usually corroded.
This from the outside, to the inside. VW never seemed to learn to  paint
things black and not have the  paint flake off. Pulleys included.Check the
inside of the pipes and you will see that they are perfect.

The quick cheap way to do this repair ,is to cut the bad section off with a
hack saw and replace it with a universal radiater hose.Works great,but is
ugly. Ugly is not bad.I have seen this repair many many times. It will get
you going and keep you going.

Another way to do this ,is to  find the fiberglass coolant tubes from a
late 85 vanagon that(Same pipe as you). These are a direct fit.The steel
straps /screws are replaced with a wire hook.

Ebay has someone selling the stainless steel pipes,on occasion. BD will
sell you stainless steel for a good price.

What ever way you go  , when replacing the pipes, the gas tank needs to be
removed.It is a tight fit in the rear area by the engine. With fiberglass,
you will need larger  diameter rubber hoses that go  from the front of the
tubes, to the radiater.

Lastly, if you have power steering, corrosion is about to make a hole in
one of those lines too. Maybe replace these , at the same time.If you drop
the tank, maybe put new gaskets in to reseal it.