What kinds of mods have to be done on the block to accommocate the Hemi crank both 604 or 572. Bottom of bore mods for each and modifications in the oil pick up area. Any other mods need to bee done to the block. Pictures would be great if available.

I used a 2.2" rod pin on my 4.75" crank, very little grinding needed for rod clearance on my siamesed bore block. Of course you must go with external oiling pickup.

With the 4.75 the 2.2 rod does create more room and the crank like you said does take away from putting an internatl pick up in the motor. With the 4.50 crank and the old world block that I believe is the Mitchell block or looks much like it will worked with an internal pick up with some extra work. I like the external with a swing pick up in the pan with a much bigger and better pump and the line running to the front of the block. Just can not remember how much of the block needs to be ground down to except the 4.75. Frend built his and can not find his pictures of the work so I can show this to another friend. The friend has not decided on 4.50 or 4.75. He will be running the Eddy Hemi Heads and is leaning toward an Ohio Crank Rods and Pistons order for the motor. All read any most with good information on this kind of build, so keep them coming.

I have a Bill Mitchell aluminum block, 572 CID with 4.500" stroke and 2.2" steel rods. They fit with no block clearancing. I never tried the internal oil pickup, went with external line.

I found out yesterday that my new (five or six years ago) KB aluminum wedge block with an older KB forged steel fully counterweight 4.500 stroke crank with stock rod journal size (2.375) with set of Scat forged H beam rod bolt heads won't clear the sleeves at the bottom of the cylinders
Time to get the small die grinder out and start removing the material from the problem areas

When I ordered my KB block in 2005, they asked me what stroke and rod combo I was going w/ and had the bottom of the bores notched to clear. I told them aluminum rods, even though I was running steel, to get the clearancing done in case I changed later.
Oddly enough, when I was fitting everything, the front counterweight on the crank hit the block and needed a small notch. All the rods cleared just fine.

Along that topic...

I am using a Callies 4.500" crank in my BMP block as I said above. My early mockup showed the crank counterweights cleared. But for balancing (B1 pistons, not hemi), I had the counter weights reduced in dia. Then it only needed a small dimple to balance, not a bunch of big drilled holes in the counterweight.
572 CID B1 engine build - Part 3

The counterweights were 3.79” radius (7.58” dia). The front and rear are 1.23” wide, inners are 0.78” wide.