396 SBC 3.875" stroke = 1.94" "throw"
2.10" rod journal/2 = 1.05"
2.45" main journal/2 = 1.21"
1.21+1.05-1.94 = 0.32" overlap between the journals

383 SBC 3.75" stroke = 1.88" throw
2.10" rod journal/2 = 1.05"
2.45" main journal/2 = 1.21"
1.21+1.05-1.88 = 0.38" overlap

396BBC 3.75" stroke = 1.88" throw
2.20" rod journal/2 = 1.10'
2.75" main journa/2 = 1.38"
1.10+1.38-1.88 = 0.60" overlap

454 BBC 4.00" stroke = 2.00" throw
2.20" rod journal
2.75" main journal
1.10+1.38-2.00 = 0.48" overlap

Of course, the BB is going to make more hp. If we try ci/in of overlap.
383SBC/0.32 = 1197
396SBC/0.38 = 1042
396BBC/0.60 = 660
454BBC/0.48 = 945

I never worked these numbers out before. They make sense to me and support my bias about clearances and also that when you build a small block stroker, if it is going to make power and turn rpm you damn well better get a good crank.

If you can't visualize this, take a look at this crank:



Probably not as rigid as this one:



You can easily visualize "overlap", or lack of it, in these two examples.

Rich