Ok, after everyone's feedback I was able to get the
chops for Oracle -> Civil Service in on Turn 77.
The empire development did not suffer nearly as much as Turn 76 chop into Oracle.
Silver City did not get a Lighthouse, and that is about it.
Key changes were Rex only chopped 1 forest instead of 2 for Canal City.
This is because it was possible to add Turn 59 - Turn 63 1
per turn to Great Wall in Canal City.
This led to 86/150 after the chop, and later on Turn 68 I was able to work a 2
hill to get 90/150. (no chop required)
I looked at it every possible way to get 90/150 during the singular chop on Turn 64 trying to free up T68 to add some more Great Wall fail gold in Cow City, but Canal City just does not have 2
to spare.
The saved forest in Canal City let Rex go back and farm up our capital 5 turns earlier.
Science City did NOT 1-pop whip 30 more into Great Wall to go above 150.
The extra population got Library done faster and later got x2 scientists to work at Size 6 for 1 turn.
Probably a loss in beakers, but the capital is better off with more food and less whip anger.
Turn 77 Oracle -> Civil Service all depends on getting our Stonehenge 116
gold by Turn 67. 
With 116
from Stonehenge by Turn 67, I ran out of gold around Turn 76.
T75 - 100% slider Worked 2 scientists in capital for 1 turn since the city reached Size 6.
T76 - 80% slider (whipped Dun in Science City)
T77 - 60% slider (thanks to +10
overflow from Dun whip in Science City)
Need +49
more to run 100% slider on T76 and T77.
We had 10
to spare at the end, so
T77 Oracle is pretty tight with good empire development and careful use of forests.
If we hit Turn 67 and Stonehenge is late, we might want to consider Turn 75 Oracle -> Currency
Currency is half as good as Civil Service, we don't need Code of Laws (just Math), the trade routes give just as good an economic boost as Bureau, and it gives +20% research bonus for Code of Laws.
If the AI completes Great Wall, we get an extra chunk of coins.
In this scenario we could just build Great Wall fail gold into the 70's and limp our way to Math and Currency.
The Dun whip in Science City on T76 at the same time Dun was whipped in Profit City led to a huge +50
overflow and +10
extra too on T77.
With 2 +24
chops landing T78, and a revolt to bureau, Science City can have 352
in Mids on Turn 80 I think.
Dun whip in capital T76 makes sense because Bureau +50% hammer bonus will mess up the sweet 50 Dun overflow by capping it to 33.
I'll try to have the PPP micro up in 12 hours.
Turn 56 the northern island will have x3 fish and copper hill right?
Please give a thought to Kremlin and if we really want Great Wall.
We don't have to commit to Great Wall until Turn 69.
45 whips are so sweet if we can build Kremlin fast enough.
A shame State Property is an almost useless Civic for us.
Oracle in Profit makes too much sense.
Free tech + Marble in the future + General City can go somewhere more important.
Civil Service remains compelling because after that we can tech Paper with Representation Caste Scientists and we can double bulb Education for extremely fast Oxford with only 1 University needed.
Note that Education comes before Alphabet and Philosophy.
https://www.civfanatics.com/civ4/strategy/references/great-people-tech-preferences/
?
on T55 because we traded away two health resources that we only have a single copy of (although in the final save it looks like it's only sheep so we netted more seafood). The fix is easy, just cancel trades with SB in the real game as required as we get 
in our cities. Be on the lookout for it so you cancel the trades at the correct time. I updated the test save by trading away the same resources on T55 to SB. Use my updated test save to make sure that the MM still works and to give you an idea of when you'd need to cancel the trades.
