The basic kit for the solex (weber look-alike) is around $100 per carb. $500 for both might be a little steep, depending on the work done. If you have the money then take it to someone with a dyno and knows what that are doing.
I have heard of a guy here in Perth (I am sure there is someone in Brisbane who does the same), that actually solders up the jets then re-drills them to suit. All the work is performed with the car on a dyno and with a gas analyser. The work was done on a mates rally car and he could not speak highly enough about the results.