my question would be... whats the compression like on that small block to get those numbers in comparison to the B series 383?
I would actually say go with the Big Block 383 is the power level is going to be the same. The big block is gonna be making the same power, with less stress and less cost than the 318 stroked., in theory anyway.
From an economy standpoint, I depends what the engine is replacing. Small block out, small block in would be pretty simple. If you switch to big block, the cost will add up quick.