Mine was from a 91 or 92 Dakota 318 V8. The reason I suggest Quality Engineered Components for the adapter is my torque converter bolts were a pain in the a$$ with the Wilcap, much easier with QEC one, plus he can answer any HEMI questions you may have.
http://www.qualityengineeredcomponents.com/
With your 276 HEMI, you do not have to do the internal mods I chose to do. I've been building transmissions for 25+ years so I can't leave them alone, lol. If you end up with a 2 wire A518 with lock up converter, that's perfectly fine. Several aftermarket places make very very simple kits for the lock up function.
Adam
EDIT: With a 276, I would also be on the lookout for an A500 O/D. Basically the 904 version instead of the 727 version the 518 is and smaller sized. It should handle anything your 276 will put out. Just make sure you get the correct bellhousing.
These transmissions come with a .69 overdrive, so unless you're running short tires, I'd up the gear ratio to at the very least 3.73+
1 more EDIT. Check your torque converter bolt circle. Make sure it matches the flexplate bolt circle, Ma Mopar had 2 bolt patterns for the torque converters.