I remember been a PITA with Rob Shape ( ATI ) , i asked him for a complete powerglide supercase for sb mopar, his answers were:

We can sell you just the case and adapter. The case is $693.26, and the
adapter is $125.09 We are still in r&d on the SB mopar bell

not sure on an eta... still trying to work the bugs out

And then on April 01 2008 i recived this email from him.

Complete kit is now in production (bell, case, flexplate, adapter, and hardware). Price is $1310.30

Give it a try....i have tried both the adapter plate with oem powerglide, then a glide cut for JW bell, you won't be disappointed
Btw they did sent the ATI powerglide to me without the adapter spacer to...i might have the first one i have to check the serial

As a matter of a fact i just finished doing some sheet metal work to my 65 valiant firewall, o well i did try to stay as close as Original possible but with an engine moved an inch back you get all kind of free problems.

Btw iam about to send the ATI case to get the internals in, to Mobile Alabama in the next couple of days,i wonder if i only need to send the Case and Tail housing?