I am going from a 75 1.8 to a new 2056, will the 1.8's distributor work?
are the stub pipes the same?
is there that big of a difference betweent he heat exchangers? (1.8 vs. 2.0)

The distributor will drop right in but may not be the best choice for performance. What stub pipes? You really don't want to use the '75 exhaust system. If you backdate the exhaust you'll need heat exhangers, muffler and hanger. Find all the parts from either a 1.7/1.8 or a 2.0 as they can't be mixed.

by stub pipes I meant the ones coming off the heads, are they all the same?

Actually, the 1.8 L-Jet distributor is a far better advance curve than an 009... it is very close to to the 050 curve. Lots of engine guys I know use them. And if you hook up the vacuum retard, you get an advance kick to overcome flat spots when the throttle is opened.