Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
These days, there are likely a lot of conversion kits available. Your biggest hurdle will be the rear end you have. It is likely an 8 1/4 or 9 1/4 rear, meaning that the axles are held in with a 'C-clip' in the center of the housing. You will need to pull the axles to get the drum brake backing plates off (requiring some disassembly or the carrier gear set).
Just throwing this out there.... many years ago I had a 77 Cordoba that I hopped up. A shop installed an 8-3/4" rear end for me (told it was from a '75 Charger, I can't say for sure) and I believe that it still had the "iso-link" suspension (again, can't say for sure).
Point is, there are definitely rear disc setups for 8-3/4" rear ends, and if I recall correctly, the axle perch-to-perch distance on a 79 300 is the same as a 70 Plymouth b-body.
Make sure you know what rear end is under the car and then call a few places and see what they say. I'd start with DoctorDiff and Baer. If nobody has one off the shelf then figure out if you want one built or not. It isn't very difficult to design a rear disc setup but it does take some time and knowledge.