Transistor VBE-matching circuit is ready and working. Here is a picture of my measurement setup. The desk fan creates a stream of room temperature air for transistors and the meter. Transistors are moved with tweezers otherwise the finger-temperature would ruin the measurements. I let the setup stabilise some 15-30 minutes before measurements. After the transistor is inserted to circuit I wait also some 1-2 minutes until the voltage stabilises. With my multimeter I can match the VBE to +/- 1mV. I hope this is enough. I read that in original ARP-2600 the transistors were not matched at all so this can not go wrong anyhow.