Forgive my ignorant question, but can you get the same performance from a 850 by changing the jets as you can a 750? I would think that the size of the venturi would affect flow speed regardless of jet sizes, but a buddy of mine thinks that simply swapping jets will net the same effect. Thanks for any insight.

Guess I should clarify...that if the 850 were too big and you wanted a 750, could the above situation work?

You are correct.
Changing the jets only effects the air/fuel ratio.

Because the 850 has a larger venturi bore the low speed responce will be slower.
Kinda like sucking liquid through a small tube then switching to a large one.
Less velocity, more flow.