@buzzard
Had another couple of listens through... because you've lifted the bass-line an octave or two, it's sort of taken away the low-end drive, (vs the original), assuming you're trying to achieve some degree of familiarity. On the middle-8, the background arpeggio is more prominent than the lead line. I think it's partly because the notes of the arpeggio are long, (almost joined). Maybe shorter note-lengths would ease it back in the mix..
The slow-down, towards the end is quite steep and feels a bit awkward, (to me anyway). If it's there just to add a bit of variety, I'd maybe lose it and find something else instead. If you put a more constant bass-line back in, you can always drop the bass-line for effect, (from time to time).
Another possibility, for variety/effect.. Instead of just slowing the tune down, take a finished mix [without the slow-down], minus the drums, (.wav file) and.. at the part where you slow the whole tune down, slow it down in an audio editor, (goldwave/audacity, etc), I would say, slow it quickly over maybe 1 bar but then build back up more gently over 4 bars... Put that back into your DAW and sync your drum-track to it.. (I've definitely heard that effect done before in dance tracks).. The pitch of the whole track drops with the speed but the drum-kit stays solid at it's normal pitch.. It will take a bit of work to do it but the finished effect is quite dramatic.
Another trick is to use a phaser/phase shifter on 1 section... this is another thing I've heard previously on all sorts of tracks.. Obviously, this is done on the final .wav file in an audio editor.. select 1 verse/measure etc an apply a shifting phase to it.. the tracks goes thin and then gets fat again.
You could always add harmony notes to the lead-line.. That would definitely make it stand out more.. The SID track is/was limited by the C64's 3-note maximum.. You don't have that restriction.. If you use a high harmony, it needs to be a fair bit quieter than the lead-line or the whole melody will sound off & weird. Low 3rd harmony works well, (I use it a lot in my remixes)..
Hope at least some of this is useful...