Majority of the under plenum coolant hoses can be replaced with regular (straight) hosing -- no special bends required. Hosing used is the same size as for the fuel lines -- 5/16. It's also a good idea to purchase new springy clamps for all those connections - since likely the ones on your car are already pretty old.
However on an NA - there are 3 rear hoses (2 on psngr side, 1 on driver side) that bend a certain way and I used stock (formed) hoses as replacements. This picture should help explain:
PS - Some folks elect to eliminate all of those hoses and just bypass the feeds in the rear - simplifies the entire system....
Yes - stock hoses have those restrictors as well.... - 
