they are interchangable as far as spoke length,I relace my original trek cc rim and wheel and the original spokes worth fin until the rim cracked,so I had an old steel wheel from my old wal-mart bike and trimmed the spokes to the length of the coaster brake spokes, wheel and its fine now.
The hi-stop hub you have are used on those wal-mart bike and those department store cheappies.As fo r the rear sprockets sometime the manufacturers make the inner hole metal a little thinner which mean your sprocket will have a little play in it and you will have to either find a washer/spacer or get the proper sprocket.
go to your LBS and try some.