I currently bought a complete Vq40 engine which was mixing oil/water for $500, that will be swapped in my E30 bmw when I finish rebuilding it and sourcing the other parts needed.

Since I will be rebuilding it, I'm currently in the search for some OEM solution to make the compression higher.

Vq40 specs by SR20DEN:
Rod Length (center dist): 166.87
Rod Stroke Ratio: 1.813 (92mm stroke)
Pin dia. w/bushing: 22.0
Rod big end dia. : 57.0

Has someone compared the Vq35,Vq35HR,and Vq40 pistons? I know the vq35 rods are shorter, but the Vq40 block is also taller than the Vq35HR's block.
Would the Vq35 pistons fit? What compression ratio could they yield?

If not... Also thinking about making a VQ30/40 hybrid.. that way I wont have to tamper with the block but leaves me with what are the exact mods for these heads to be used with the Vq35de Valvetrain..