Sources went through temporal noise reduction, and when needed (usually with MPEG-2 sources) deblock and/or sharpening and/or dehalo.
Using more than one source helps to get some details back, even if the whole process is far from perfect - “guessing” details sometimes, losing them other times…

I downloaded Emanswfan’s 35mm 4K Filmized ROTS test clip; I like a lot his color grading, so I applied it to my test clip (just increased the gamma for the luma, though); added also a finer 35mm grain plate.

Comparison: http://screenshotcomparison.com/comparison/131243
Test clip: http://www.filedropper.com/rotsuhdtest (only 10s, just to have an idea)

Opinions are welcome as usual.