I purchased my van up in Washington state and the previous owners rebuilt the engine and I assume they may have also rebuilt the carburetor last so I would also assume they built it to run at sea level and now the van is about 5000ft higher elevation. If I understand correctly the higher the elevation the smaller the hole correct?
If my carb has what is roughly two #64 jets then I'm looking at getting something in the 50's??

Edit: I read that for every 2000ft increase you want to decrease the jet one size...
According to that scale I should get a #61 & #60... I think... Assuming whoever installed those jets did it correctly...