I am in the process of fitting seats in our cuda, I did it on my challenger, with some recaros and ended up using the stock mounts with some square steel bolted to the steel part of the bottom of the seat and then mounted the stock units where the needed to be and used the stock holes in the floor ,and lined it up,welded it together 15 years ago, and they work great.
With a bad back the stock seats dont have enough support so I really like having a comfy seat for long road trips , they pay off in the end.
Now I have to find some seats ,like alot of people here, so far no luck with craigs list as of yet