I found a good video on someone explaining how it works.
https://www.youtube.com/watch?v=9tepFx1uMJo
The re-manufactured manifold sold by rock auto/amazon is made by ATP did come with a very rough casting, especially on the inside. For me it really was not a deal breaker because i'm not looking for performance. I just wanted something I didn't have to worry about cracking/getting worse with time. The original would likely have continued to crack.
The re-manufactured manifold design added a LOT of strength in the weak spots. Where the old flange is about 1/4 inch thick (where the bolt goes through) the new one is close to an inch thick. It comes with 2 studs for the intake manifold to bolt on, and 3 studs for the exhaust side with 4 or 5 holes for many different exhaust applications. It includes the heat riser weight with spring. It does not include the 'auto choke' id call it for the carb or mounting hardware but it does have the spot for it and tapped holes. I easily removed it from the old and made two bolts for it. Like I said if you're not looking for perfection its a good deal for 167$ shipped. I don't think you could ever get the inside smooth with even a carbide bit, some areas are unreachable, i didn't bother. Also the flange is completely straight, I checked it with a straight edge. If the manufacturer would take the time to clean the surface up on the cast this would be an incredibly nice reproduced manifold. Pics later