A LUT is probably as good as it gets. Assuming that you are using software like Davinci Resolve, the LUT file is put in the LUT directory so that you can then apply it to a clip. That will transform from your source image A to your target image B but for that to give you the result you want, you have to be quite specific what A is. If the LUT assumes that you have a flat log image or a Rec 709 then that is what you must give it. My personal favourite group of LUTs are a set that takes Cinestyle flat video from my Canon camera and emulates two types of Fuji film stock and two of Kodak.
It does sound (and maybe is) very daunting and there's clever folks here tutting at my rather Neanderthal methods but Resolve is free and many of the LUTs are too.
http://www.cineplus.ch/vistalut.html They claim "VistaLUT doesn't pretend to replicate a film size... but it represents the 70mm color timing culture." Strangely, I didn't like their example videos. I thought skin tones were too bright but that might be just me.
Basing your colour grading around a film emulation LUT may be the way to go. Also NFS had an article a while back that had a giveaway of LUTs that matched the looks of certain films. https://nofilmschool.com/2015/08/7-free-luts-based-iconic-movie-looks-pl...
For M42 lenses like the Helios 44 on cropped sensors there are often focal reducers to squeeze all the full frame image onto the sensor gained f stop and reducing focal distance.
If you are looking to use the Helios 44 as your "50", actually it is 58mm then you can make up a set of 37mm Mir 1b, 58mm Helios 44, 58mm Jupiter 9, 135mm Jupiter 11A or 37 and 200mm Jupiter 21m. As these are all CZJ based you can usually swap in CZJ Flektogon, Biotar and Sonnar.
You need the powerhouse computer to work with 4K+ video in Resolve 14. If you aren't upgrading the camera then the computer seems irrelevant. It isn't that it is impossible to shoot good video with a Rebel, people can and do. Lens upgrade? Maybe. One or two Yongnou, perhaps vintage glass, Helios, OM, CZJ, FD etc. You would still have a lot of change left. Certainly make sure that you have decent sound kit, perhaps lighting too.
The most important part of the entire system is you. Even for the guys here with the most expensive kit, they are still what makes their stuff so good.
Had a think about this. CR files are proprietary Canon aren't they? If your Mac isn't set to handle them then they won't show up. The Mac hasn't a clue what they are. I think that you have to use the Canon software or at least install what you need to for the Mac to know what they are.