Bell-housing alignment help

OK, not to derail a happy thread, but I've got the same problem.

I've got a 360 stroker from Muscle Motors in Lansing, MI, and a Quick Time bell plus Tremec 5-speed, shipped as a set from American Powertrain.

Dialing it in, I have 52 thousandths (0.052) of runout (max number dial reading minus minimum dial reading)

The dial goes back to 0 after a full rotation, and I have no wobble or play in the mag mount. I get this number very consistently, either with the flywheel on, or with the dial indicator base placed directly on the face of the crank. I get the same numbers whether the block plate is on or off. I've measured repeatedly, with the bell removed and off and remounted between each. I'm putting in all the bell-to-block bolts, and each is properly and consistently torqued for each measurement. I've inspected the inside ring of the bell and there are no ridges or burrs, nor can I find any on the back face of the block or the front face of the bell. I've dialed it both with the bell alone, as well as with the adapter ring that reduces the hole diameter to match the Tremec tranny face. Throughout all of these different attempts, I get the same number, spot on, every measurement. The dial sweeps smoothly from full deflection to full opposite deflection as I make my way from 12:00 to 6:00, and back. There are no sudden jumps or irregularities that would indicate surface finish problems. There is not excessive slop in the dowel locating holes in the bell.

The runout is straight down -- in other words, the bell housing needs to be shifted straight down in order to correct the runout.

My dad had ordered a set of .021 offset dowels. Knowing that wouldn't be enough, but just to check my measurements and methods, I mounted the bell with the .021 offsets in, and dial indicated. I'm left with 10 or 11 thousandths of runout remaining -- in other words, the needle swings +5 at the top of the bell housing, and -5 to -6 at the bottom of the bell.

From what I can read, the tranny wants less than 5 thou of runout, and I'm still stuck at 5 to 5½ thou, even with the biggest offset dowels that are available for purchase, and needing to use 0.021s seem like a crazy adjustment, if everything is right.

American Powertrain says that QuickTime CNC measures all their bells and so it has to be the block.
Muscle Motors says that Mopar wouldn't ship a block that bad so it must be the bell.

I don't have a second bell that I can compare against because the original engine was a slant 6 with an automatic.

I don't know what else I can do. Do you guys have any thoughts on what I can try as a next step?