sounds pretty good,
personally, I owuld reconsider the disk brakes and the suspension fork. If it were me, Id rather have a rigid frame and fork, and use bigger tires as a form of suspension.... Much simpler, lighter and less to break.
8 speed allows for a slightly tougher chain. its possible that this is stronger, Im not convinced, but if it were me, Id probably err on the 8 speed side of things too.
shifters, friction. I would look for old thumb shifters on Ebay, some XT or suntour shifters... avoid paul thumbies because they are pricey. you can get the same thing for less if you look around. Scour the thrift shops ofr an old MTB and rob the shifters off of that, or call the local police and see if they have a stock of abandoned bikes. you should find something...
If you do get a sus fork, marzocchi is good. look for an older version of the Z1, coil, oil, tough as snot. heavy though. Make sure it doesn't have a 20mm axle! (but Id really reconsider on this
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