I've recently purchased a Hallicrafters S-120 -- 4-tube superhet receiver from the 1960s, continuous tuning from 540 kHz to 30 MHz, bandspread control, and a regenerative IF that doubles as a BFO for SSB and CW reception. Someone before me appears to have worked on the set, as the capacitors seem good (no hum, good reception for the antenna currently available).
What I've learned since receiving it, however, is that this set lacks the selectivity, stability, and fineness of tuning to make a good communications receiver; that is, it's for listening, rather than the listening side of two-way operation. While I have tuned in CW, digital, and SSB transmissions, the latter especially are hard to really clean up. AM transmissions in any band come in very readily and clearly, assuming they're above the noise floor.
With a limited budget, however, I'm looking for a better receiver for use when I get on the air (likely mainly CW, as a CW transmitter can be had fairly cheaply). I need to be able to tune across a band to search for calls, hear the spot tone to set the transmitter, have support for muting when the tranmitter key is down (or the ability add it), and by preference, I'd like it to use vacuum tubes.
What do I need to look for (that can be identified from photos and eBay listings that usually are intended to hide the faults of a piece) to distinguish "listening" radios from "communication" receivers?