Will they work?

Do you have 1974 or 1975 1.8 heat exchangers? They are different. Either set will fit a 2.0 engine as long as you have the complete set of parts. Heat exchangers, muffler, muffler support etc. Both 1.8 sets are not as good as the 73-74 set of 2.0 heat exchangers!

Right now I have a set of '75-'76 H/E's. I think I remember someone saying that anything is better.

75 and 76 1.8 and 2.0 heat exchangers are exactly the same. The problem is that the exhaust flows forward first then bends and goes toward the rear of the car. Probably the 74 1.8 exchangers would be better,(they flow directly rearward, but are smaller inside diameter then the 75-76 style and the 73-74 2.0 style.