Vintage Cars: 1982 Mercedes 380SL, vacuum advance, sel

Question
My 1982 380SL had a 420 SEL engine installed in it by the previous owner.  I found out that he put the 380 intake and distributor on it.  The power has been lacking but runs O.K.  Uses alot of gas.  I was checking the distributor and found out that the vacuum advance is not working.  Should I repair the vacuum advance or replace the distributor with the correct 420 sel distributor?

Answer
a non working vacuum advance will kill your horsepower while you are getting up to speed and also use a whole lot more fuel.  I'd source a engine specific distributor for that engine, set timing slighly advanced of specs, and you will feel her fly.. Just make sure you place the distributor exactly in the same orientation or you will have another set of issues