Some of your problem with the windows might be that the tracks the windows slide up and down in are worn out..... (felt is gone)
If thats the case the power windows will have the same problem
You should be able to buy the window track (channel) from a good glass shop or they can order it........ Here in So.Cal. C R Laurence is a big supplier
For a window kit just make sure you get one that replaces all you old stuff There are some on the market that use your old regulator
The first on I bought turned out to be that way it ran bout $130
I now have eletric life kits on both my cars and have had no problems....... but they do run bout 200-250

MM64

www.rgkustoms.com