Zenith carbs, which is what came on GMCs, were made for a specific engine. A Zenith from a 248 or 270 might "work" on a 228 but you can't expect the kind of performance as from a 228 Zenith. Many people have thrown Rochesters on GMC engines. Again it will "work" but not like the original carb.

"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.