Unless you wish to change manifolds, I would suggest using a single barrel carb. For the 261, a Zenith 228 series from a GMC 270 would be an excellent choice; as would one of the size 3 Stromberg universals; or possibly a Carter YF from a Foorrdd 300-6.

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop