If you could find them it would probably be better than my home built but it's only 6 transistor so here we go.
I pulled the clip leads away and this is the circuit. The round red thing is the transformer I had on the negative supply lead. The junction between the two resistors are the positive supply point. That's it 6 transistor, 2 resistor, and 1 transformer = Gilbert cell.
My project at this time is an 80 meter receiver I might build that circuit into it?
I made a couple of long tailed amps using 2SK2539s and they worked quite well. Now I'm looking at a Gilbert's cell using the JFETs.