'Normalising' doesn't tend to affect dynamic range, so it should sound ok. All it does is to boost everything so that the peak level is at what you set it to be. It's a bit like turning the volume up.
The difference between older recordings and modern ones is that modern ones tend to be more heavily compressed. This means that there is very little difference between quiet bits and loud bits (the dynamic range).
In old recordings, you'd get a peak level, then the quiet parts would be several decibels quieter giving you highs and lows of signal.
In modern ones, everything is basically at the same signal level making the quiet bits sound relatively louder compared to the peaks.
This means that even if your old recordings and new recordings are at the same signal level (usually 0dB), the modern ones will still sound louder.
The 'smart volume' options work by applying this compression to everything, trying to even out peaks and quiet passages. Personally, I think it sounds pretty terrible.
If you wanted to play around a little bit, you could get some audio software and experiment with compression on your older recordings. But essentially all you can do it turn up old CDs and turn down new ones.