"Four-plus-rectifier" was a fairly common lineup in a typical domestic valve/tube radio.
The first stage is most likely a triode-heptode converter, also known as a frequency changer (the triode section is the oscillator, the heptode the mixer). Second stage will be a pentode IF amplifier, third stage is most often a double-diode-triode used as audio amplifier, detector, and AGC. The fourth stage will be a pentode or beam tetrode audio output.
Can you still read the valve numbers? That would be a start at identifying the basic stage lineup.
