There should be no surprises other than the orientation of some components.

If you are building just an MMU then omit RN1, C1, Y1, U1 and U2. If you are building just a CPU omit U3, U5, U6, U7.

Only populate C1 if you are running at a lowish crystal speed (try without first). Remember that the 80C85 crystal input needs to be twice the clock frequency. You may want to pick double the classic RC2014 frequency for it if you have cards that need the clock 'right'.