Howdy CB:
If you have a '72 Maverick with a stock 200 you will likely have a Carter YF carb with an auto choke and cable linkage. It is rated at 187 CFM.
While the '72 does have a distributor with centrifugal advance it is still the point type. A change to the '75 and later DuraSpark II Electronic Ignition would be a step up and provide a good foundation for later mods.
If your head is a DXXX casting it could have induction hardened exhaust valve seats, but a larger 1.75" carb hole. A better head would be a D7XX or later for an increase in intake valve size and hardened valve seats. Any head needs a performance three angle valve job, and back cut intakes. Be sure to check volume in centimeters and figure Compression.
Your choices for a one barrel upgrade are to a later YF- they were used on 250s in the very late 70's, with a slight increase in CFM at 197 (IIRC). A YF was also used on the big six family in the late 70's and early 80's. The Carter RBS was first used in 1970 on 250 engines and remained until late 70's. It is rated at 215.
Any of these would be well supported by a cold air induction air cleaner system.
A two barrel with an adaptor is a good move up, but only a half a step as compared to mounting it directly to a modified manifold. The cheap way to go is to find a 1.14 Autolite from a '64/65 289. Get the air cleaner assembly, pheniloc spacer and gas line fittings. Watch hood clearance on install. This carb will be jetted about right for most elevations. low speed air screws will have to be about 3 turns out, give or take a half turn.
Adios, David
