Lufthansa investigated the possibility of re-engining their B727s with 2 X 30000 Lb engines with a totally new (Boeing built) Section 48
Yes - it was one of many re-engining schemes on the drawing board in late 70's/early 80's. The DC-8 series 70 was the only one that made it as a retrofit, and of course the 737-300 totally revitalized that bird.