Bench-Bucket Front Seat Mount Differences?

My 1970 Challenger has the rare bench-bucket front seat. The seat back left side bar support cracked and also the driver's side seat bottom springs have broken, so it needs welding and major repair (I guess that is what happens after 380,000 plus miles!). I need to find a different seat to put in the car while the I repair the original one. Are the seat mounts different than the cars that had the individual bucket seats? Do I have to get a bench seat from a B body to fit without drilling more holes? Or could I use just the driver's side bucket seat from another E or B body?
I also don't want to spend a lot of money on a temporary seat. Any suggestions?

Thanks for your ideas,
Bruce