Variable Voltage Regulator Using LM723

Hi, I am trying to build a variable voltage regulator using a lm723.
how do I go about designing and calcultating values for the various components or what steps do I follow to modify an existing circuit
I need to have adjustable current between 100mA to 600mA as well as voltage between 2v to 5v.
I know the attached circuit does not meet my needs, how do I modify or design one to meet my needs and once modified can it meet my needs?

Here is an attached circuit
Parts List
B1 40V/2.5A
C1 2200uF/3300uF
C2 4.7uF
C3 100nF
C4 1nF
C5 330nF
C6 100uF
D1 Green LED
D2 1N4003
F1 0.2A F
F2 2A M
IC1 LM723 (in a DIL14 plastic package)
R1 1k
R2 Pot. 5k
R3 0.56R/2W

R4 3.3k
R5 4.7k
S1 250V/1A
T1 2N3055 on a heatsink 5K/W
TR1 220V/17V/1.5

Bearing in mind I'm new to circuit desgining and modifying.
thx

You mite what to have a look at the data sheet for the LM723.

Astron used the **broken link removed** extensively in their line of linear regulated power supplies made mostly for Ham Radio applications. Here are a collection of schematics. Look at the **broken link removed**

I have a model of the LM723 and a running simulation of an example circuit for LTSpice.