Hey Rod,
After owning a few red motor Holdens with various Twin and Triple carby setups I would recommend the following steps:
1. Check the timing and other electrical parts and set or renew as necessary.
2. Confirm the jet sizes in your carbies are the same and note the size. You may have to change the sizes up or down depending upon your engines requirements. This will be affected by valve size/porting/exhaust etc - you obviously have to be able to burn the fuel you pump in, otherwise there's no use putting it there
3. Buy yourself (or borrow) a carby balancer (Rares Spares has them). This tool will help you to accurately setup the linkages and is a key to ensuring the carbies supply even amounts of fuel, both under accelaration and at idle. Spend lots of time and care here and you will be rewarded with smooth idle and power delivery.
4. Set the idle mixtures using an analog tacho, gas analyser, or vacuum gauge.
TACHO: Adjust each mixture screw in all the way then reverse out a couple of turns and start the car. Now adjust each screw in/out until the maximum idle speed is achieved.
GAS ANALYSER: Not normally available at home
but the most effective method. Mixture should be set so that CO2 levels are at their maximum, about 12 to 15% for most engines - never had a grey on an analyser though so this figure may be lower.
VACUUM GAUGE: Using the vacuum gauge is similar to the tacho except you adjust for maximum vacuum minus approximately 1/2" Hg. This can be difficult if you have a larger than standard cam as the idle vacuum will fluctuate due to the valve overlap. If this is the case use the tacho.
These are general rules but should guide in the right direction.
Good Luck,
Craig.
