Howdy Matt:
This YF carb should go nicely on your 66 200 with some adaptations. 1st the throttle bore is 1.75" as opposed to 1.5" on your '66 Autolite 1100. Use the hot water heater plate under your stock carb to create a tapered funnel. 2nd, the YF uses a throttle cable system rather than mechanical linkage. If you can, take the pedal and cable system from the '73 Comet and adapt to your '66. And finally, you will need the air cleaner from the Comet too as it will be slightly different then your stock air cleaner. If it is a cold air intake system all the better.
The Carter YF is a good carb, but needs regular maintainance and needs to be kept clean inside and out. The best rebuild guide for this carb is in the rebuild kit you will buy. Study it carefully before you start the rebuild.
Know that your stock '66 Load-a-Matic distributor and carb were designed to work together. If you change the carb your distributor will no longer work as designed. You can get by by using the ported vacuum source for the distributor vacuum. Your best bet would be to upgrade to a 68-'72 point type system, or a '76 and later DuraSparkII electronic system.
Adios, David