Valves, springs and guides are available from many suppliers, I have bought several sets from C@D's in the UK and have had no problems with quality.
As to the valve seats thats hard to say without seeing them. As a basic rule if the head of the valve is lower than the surface of the head they need seat inserts. I dont know any myself but I am sure there would be plenty of engineering places in Melbourne that could do this work. You need to ask around and find somewhere that has a good reputation and works on older engines.
They will be able to fit inserts and then cut them to the correct angles. There are actually three angles involved, 60, 45 and 30 degrees. The 45 being the angle the actual valves sit against.
