I've been in contact with JW Performance Transmission about the idea of an UltraBell replacement automatic transmission bell housing to mate Slant Six (G or RG Engine) to 727 or 518 TorqueFlite Transmissions. The factory DID make a G/RG 727 as you probably know BUT they are getting scarce, and there are no factory 518s with that pattern.
The UltraBell is a replacement for the integral bell housing on an automatic transmission that is used by machining off the standard bell housing, and attaches by the front pump bolts. The blurb:
SFI-certified (except 564-92480) as flywheel shields, the patented aluminum casting of these Ultra-Bells withstands severe twisting and tire shake in even the highest-powered cars while still fitting under stock floors. They bolt to the front pump for easy installation. Each weighs 10 pounds and is approximately 600 times stronger than a factory case. Models mating a Ford or Chrysler V8 to a Powerglide eliminate adapter plates and mount the starter on to the Ultra-Bell.
Obviously, with the right UltraBell, you could hook any engine to any automatic transmission without awkward "Mickey Mouse" adapter plates.
They don't as of now make ones for the G/RG (Slant Six) engine, not because they wouldn't, but because no one is asking.
I'm interested in one more for my Dart than my Sweptline, but still, there has got to be some interest out there. If this sounds like something you might want now or in the foreseeable future, do us both a favor and drop them a note.
The availability of a 518 without Mickey Mousing it would make the slant six a lot more attractive for a lot of applications. And the 727 cases are getting a little scarce too.