vintage air short cycles

[AcampoDave]

I put the sure fit kit on my 66 it is properly charged as verified today by a trusted shop. They say it needs more air flow over the condenser at low speeds. I have a 6 blade flex fan spaced half in half out of my factory shroud with a good radiator. (It doesn't run hot.) Also have all my baffles and air seals in place . I'd prefer to stay with a mechanical fan. ( I am not opposed to buying a clutch fan if I knew which one to buy) Do you guys think it's a good idea to make a seal of some kind to go around the perimeter of the condenser? My thinking is this would force the fan to pull thru it 100%. Currently there's an open space of about an inch between the radiator and the condenser and I wonder if my fan just pulls air thru the gap instead of thru the condenser. Also, is anybody using a clutch fan they can recommended for an a.c. application? Thanks