Big block intake swap questions
If the manifold you have is really off a 413, you can stop right there
B / RB engines are what is called "B" block and "RB" for "raised" block
This includes a fairly rare early 383, not often seen
and 413-426-440
All the low blocks are (I guess) the rare old 350, and 361--most 383s and all 400s
The raised blocks used the same heads, pan and timing cover. But the raised block causes the heads to be slightly "wider apart" so the valley cover and intake won't fit between the two series
Other difference are the cranks, pushrods and distributors. along of course with pistons