don't try to change the LM301 in the CV Path except one in the Voltage processor.
LM301 are remade by Alfa Par !!
i installed many different op-amp types with additional changes for resistors and capacitors.
for now: if you want an audio path upgrade like the original 2600 (blue meanie) has installed, I can modify it in my labor.
i do not share this infos, because I won´t see this solution in other big companies 2600 clones, I spend too much time in money in this analyzing and parts.