Formula1 - you have now verified two valuable pieces of data: (1) that the progressive linkage was giving problems, and (2) a single 97 IS TOO SMALL to be the primary carburetor in a 3x2 for a 302 with progressive linkage.

My suggestion would be either: (A) use solid linkage; or (B) use different carburetors. Obviously, solid linkage would be the least expensive.

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