Either you do or don't. If you have this intake, its a spreadbore.
View attachment 1715228562
* A Thermoquad or Quadrajet will be a direct fit.
* So will a Holley spreadbore replacement, but they are oddball carbs and best for people who like to experiment.
* If you have a Holley 1850, and it physically bolts on (dual stud holes in each corner of the base), then you still need to check that the throttles will open without interference
and the mating surfaces seal bores and the PCV connection etc.
