I haven't heard anything bad about Mike's friction plates yet. You can still get Yamaha plates for $9.53 at boats.net. Maybe less at other online sellers.
As mentioned the steels are ok if not warped. His springs not so much. 650central has a bigger selection of better springs.
You can make a set of your own adapters, just drill through the set you have. A drill press and a few minutes then Allen head bolts from the hardware store.
I might shop around on Ebay, you might find quality springs or plates for less. I found a set of NOS Kibble White 70LB. springs for not much.
Leo