1~7 is a double reduction gear , 8~10 is a single reduction gear. as it is a 7 speed (3_3 speeds -2 common middle gears)
used twice ..
the Hub cog is a 3/32" thick .. so any 8 speed derailleur chain will work and you can run a bigger second chainring ,
just need the chain tensioner to take up the difference.
Ah "
The 'buffer'* that the SPEEDHUB previously had available is not longer present and this new factor must not be reduced further."
so 2.1 not 2.0 .. warrantee toast there .. buffer margin, 0.25.. is then 0.0
29F 24R wheel bike perhaps? (Ibis used to make a 26/24 wheel Mountain -Trials frame)