Just reporting back that the transformer mentioned above physically fits the chassis and appears to power the circuit OK. I did notice one weird thing: When I lift the output side of the 5554N IC and connect the control pin and -Vout (pins 11 and 12), I do get the correct +/-5.0V on on the output pins 14 and 11. However, these outputs drop to +/- 3.5V when the IC is fully in circuit. Also, it takes a moment for the compression and/or fuzz effects to kick in when I switch it on. I don’t know if this is my switch or a sign that I am pulling too much current for this transformer. I need to try another switch…