My thoughts on improvements are in my longer post, above. To my mind the most important is to get the operating points right, meaning you have to get it running first, then check voltages, and from there adjust the driver bias to get the right plate voltage, and then adjust the 2A3 cathode resistor to get the right current.
Direct coupling is a pain in the backside, no question. If it didn't sound good, nobody would do it!