Howdy Back Andy:
This info has been posted several times. You might want to do a search on both carbs and catch up.
Both carbs have a successful track record on our sixes. Both can be mounted using an adaptor resulting in hood clearance issues. Both will do better mounted directly to a modified log. Both will need adaptation and fabrication for linkage, fuel line and air cleaner. Both have both ported and manifold vacuum sources.
In a nut shell, the pluses for an Autolite 2100 are-
*very durable, and simplier version of the Holley 2300
*Power valves from a 2300 interchange
*annular discharge venturi boosters
*no gasket line blow the fuel level.
*excellent bowl venting
*possibly the simpliest carb to rebuild- ever.
*cheap and available in many cfm sizes ranging from 190 to 424 cfm
*Low profile and light weight
The minuses are-
*no longer being produced
*jets are hard to find
*cluster design limits idle and transition tunebility(Not a big issue)
The pluses for a 5200 are-
*Progressive design for excellent mileage and improved power.
*Available new or recycled.
*Parts are available
*sizes range from 230 to 280 cfm
The minuses are-
*a more complex carb, but infinitely tuneable
For all-around performance and tuneability a 1.14 (300 cfm) 2100 on a mild 200 is hard to beat for simplicity, economy, durability and improved performance. The same can likely be said for the 5200, but the 5200 may be a little more difficult to get right to begin with and more finicky over time.
That's my two cents- for what it's worth.
Adios, David