[What sort of pistons is he getting? I'd think he'd need something with a big D-shape bowl in it or a reverse dome to get the compression down.]

cp. forged and yes dished.

[How do they do that?]

longer rods increase the dwell time at TDC. if you need more info than that i'll link you to a bunch of articals and tecnical papers.

[Bore wear has never been a problem with stock stroke & stock rods.]

i never said to change the stroke, well on his motor atleast. and he will not be making stock power, he want twice that. so all the forces are going to be increased. pistons with a short pin to deck hieght are going to be more stable than the stock diesel refuge pistons. and the longer rods are going to have less rod angularity cutting down on side loads on the piston and measurably if only a couple percent, that a couple percent.

[I wouldn't be in any hurry to toss out the stock rods or stock crank, especially in the B30. Firstly, you can't reduce the size of the crankpin in a B30, like you can in a B20. Secondly, long rods don't help power at all until the cylinder head reaches it's limits in an NA motor, so increasing the rod ratio in a turbo motor is going to give away power under 3500 & never give it back because you just can't rev the B30 up that much without it bending.]

i never said to toss the crank. they are nice forged units. once again i never said to stroke it. and he isn't going to rev this to a point were the bearing speed will be and issue. we can disagree on the long rods, but you can't say that a rotating assebly that is half the weight and just as strong, if not twice as strong as stock isn't going to increase power output, let the motor rev higher, faster , smoother, and with less stress put on the crank. it going to be a boosted motor so it will get the power back that it lost in the bottom end, if it is more resistant to detonation he can run more boost, more boost more power
he is also using a turbo that will spool very quickly , so it will be making the power back befor 3000rpms.