All the rochester stuff I ever read or measured had 1-9/16 and 1-11/16 butterflies rather than 1-1/2 and 1-3/4 butterflies (like holley stuff) My son sent a pair of end tripower 2GC throttle bases to some Calif. carb guru (read "yahoo") to be bored and all they did was take it from 1-11/16 to 1-3/4 by using some THIN stamped steelmaterial that had daylight showing and vacuum leaking all around the butterflie-had to make our own about 3/32 thick and proper dia to shut down all the air leaks. It really pains me to pay for work than I could do better!
