I was offered a NEW Crower center weighted crank in 4.500 stroke, center weighted, standard bearing sizes of 2.750 and 2.375. Never been run! Asking price is $2,000. I am posting a picture of an adapter to use for an auto trans. The bolt pattern is 3.950 b.c. 8 bolt. I know this guy personally and he is a square shooter. I am guessing I will need a spacer between block and bell housing. Anything I am missing here? I assume i will need to verify the journal sizes .

KB industries use to sell a push in adaptor to use a late torque converter with those styles cranks they worked well with the early 392 hemi style crank flanges.
I'm sure that some of the tranny companies offer them also

I had a brand new LA Enterprises Kryptonite fuel crank that I used that I had cut down to Chevy rod journals to get a 588 Hemi configuration, easy enough to get the converter adapter pilot, but my existing converter required an extra 1/4" aluminum spacer plate (on top of my .090 mid plate) between the 727 bell housing and engine to get correct converter pull out due to the thicker Krypto crank flange.

My previous combination before the new crank was a Bryant forged 588 combination that was perfectly spaced without the extra aluminum .250 block spacer plate. My Krypto crank did not require a thick adapter like in your picture, just the converter pilot adapter

Randy

the 8 bolt crank in my 440 has a 3.950 bolt pattern, and the holes are tapped 1/2-20 thread.
the TC register is 2.155 OD, and 1.812 ID, .660 deep.
the 392 adapters i have also have the 3.950 bolt pattern as well as the same TC OD and ID.
however, the 392 adapters are not tapped, as they register on the crank flange OD and are sandwiched between the crank flange and the flex plate.
hope this helps if possible.