In terms of original mono, I believe I have the theatrical mono of both Dirty Harry and Magnum Force.
I have the original Rental Tape of Dirty Harry from 1979, I believe it has the Mono, albeit not great quality. I also have the 1983 Pan and Scan Laserdisc, which might have the mono as well but higher quality.
Dirty Harry Rooftop Stakeout from the 1979 Rental tape:
https://www.youtube.com/watch?v=i-eM82k-l1E
Here is the Japanese laserdisc of Magnum Force. It has burned-in Japanese subtitles, but has English audio. I also I have the Japanese VHS, which is the same as the laserdisc.
Magnum Force Robbery Stakeout from Japanese Laserdisc
https://www.youtube.com/watch?v=8pc_iEDIN4E