where are you planning on riding the bike ?

the bike looks pretty cool and well thought out...
why not use it with two wheelsets as it was intended ?

i can't think of any advantages 650C would have over 700C on the street..
ditto for 650B vs. 26" when wanting fatter tires on rougher terrain..
both the 650 sizes are a pain when sourcing tires/rims

the difference in bb height between a 22mm tire on a 700C rim and a 1.75" tire on a 26" rim would only work out to about 10mm... not much at all, really