The present keying system doesn't work reliably. I have had problems with it and others have also reported problems. A fix has been suggested that uses the same analog multi level scheme, but I think a digital key interface would be more reliable. I see that you have included something in your schematic.
By narrower filter I meant an adjustable audio filter. I'm adding a Sotabeam dual bandwidth CW filter to mine with a 3 position switch. Position one is out (original SSB filter), two is Sotabeam wide and three is Sotabeam narrow. A handy feature is that the filter can activate an led when you are well tuned and I'm adding that. The filter is placed in line with the volume control. I'm also adding the PTT audio mute pop fix from the Wiki that grounds the same line from volume control. Both are on a piece of perf board attached by two of the nuts that hold the speaker.
An alternative audio filter could be a SCAF that goes on the audio output.
For digital modes an isolation transformer and either a VOX or CAT control for PTT.
Thanks for starting a Christmas list.