If needed i can build you a custom simple file converter for a small price, although learning it yourself is always a good thing. I have made and used video software in the past, to achieve what you want for free with decent image quality and file size just use FFMPEG to re-encode the films to h.265 with a 2 pass method. If you try to use the same quality, the output will be noticeably blurrier. If you're encoding bluray sources, remember you're going to need to increase the quality from what you'd normally use for DVDs, to allow for the extra detail.

Of course when you're looking at stills, the final encode might not look impressive - but when you're watching from over 6ft away, you will be very hard pushed to see any artefacting. I don't know what target size you have in mind, but I can very comfortably encode around 90 minutes in to a 308 MB file.

Do some testing on your own sources and I'm sure you'll agree. I can't emphasise this enough, but the quality of the NLMeans encoder is visually FAR better than hqdn3d.

The output files look much better and because there is less noise for the encoder to deal with, the file sizes are reduced further, too. During my research and testing, the biggest change I did was to change the denoise filter from hqdn3d to NLMeans. I've personally used Handbrake to do H.265 encoding directly from DVDs, like yourself, to replace my H.264 files and reduce size. If you can, encode from the originals, not the current H.264 files.

Handbrake how to batch convert