Welcome. Save yourself some aggravation here and just order a rebuilt unit from Rock Auto. Prices are fair and the quality is really pretty good. I have bought quite a few carbs from them. they also have a send in and rebuild option for carbs that they do not have a good supply of cores.
For a 74 250 its like $132.00 with a core return, $65 more if no core to return, and you get a guarantee.
I didn't know Rock Auto sold them. I see the rebuilt the PO put on years ago, the numbers come back to a 1976 Chevy C10 manual tranny. I guess it was just a mix and match deal.
I hear good and bad with rebuilts, but I am willing to give it a try and see if I get a good one.
