cool info and nice result. Ubitx should be as sensitive as most any rig, as long as your antenna isn't dreadfully tiny. It might be slightly less crunchproof than a mid priced commercial rig with its preamp off, even its phase noise is decent.
LPF I would evaluate your 160m antenna as set up for swr at 3.6 MHz. If it looks like an open circuit, and you have axicom or replacement replay board, or v5 or 6, maybe. I did make a few contacts like that, but now I built a low pass filter in a small altoids tin as I had the parts, male bnc connector on one end so its easy to use.
I wish folk still did conversational psk31. I think it was killed by folk's long brag files.
Time to use the ubitx on 15m as we have sunspots.
Very close to fcc monitoring station !