Discrete designs using operational amplifiers work but are not very practical now compared to integrated regulators, and operational amplifiers have a performance disadvantage in dual loop designs because of integrator windup.
The reason I mentioned the MC1466L as an improvement is that it has the same operational transconductance amplifier as the 723, but has two of them with parallel outputs so switching between voltage and current limiting is seamless. There are modern switching regulator controllers with the same arrangement.
The same thing might be accomplished with an externally compensated operational amplifier like the 301A or 308 but that is hardly a modern solution. I have seen a couple of power supply designs now which used two 723s with the error amplifiers paralleled to do it. A general purpose single/dual/quad precision OTA as a universal building block would be ideal but the closest thing is the LM13700. Tektronix used a lot of dual transistors in their regulators to do this.