The air forks should logicly be better..as they have the advantage of adding air. The internal componets are the same I believe. However..the fact that they will only hold 7psi each as their limit makes this advantage small. The installation of the progressive springs and 15w oil to either types of forks would be a vast improvement. Not sure if having a few pounds of air would be that noticeable. Filling each leg precisely the same is a challange also. Progressive does make a fork balancing kit that connects the two air valves and would make filling easier.
You also have to carefully examine older forks for dents, and scratches..as this would shorten the life of the seals and possibly cause leaks. I think for the trouble involved and slight benifit..you are better off with new forks as opposed to the older ones, but having an extra set of forks around can save you some $$$$ if yours get bent.
Install the progressive springs and if you have the $$ the SuperBrace fork brace .. this will make a much better improvement than using the air forks..
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