Technical Mercruiser 120-140

I am buying a Mercruiser 120hp
I have 140hp, bad block.
Can I swap in the 140 crank to stroke the 120?

 

I don’t know as the blocks are identical to be sure. But starting in 1991 the 3.0L blocks were one piece RMS with the rotating assembly totally different than the earlier engines

 

need 140 rods as 2.1 vs 2.0 journal and don't know anyone making pistons for 3.875 bore with 3.6 stroke