There are 2 species that are mostly found in FW but often visit BW but do best kept in BW in captivity: The F8 (T biocellatus) & Redline (T erythrotaenia). The GSP is rarely found in the ocean but many of us keep it in marine conditions in captivity with good longevity.
Throught the 10+ years of running The Puffer Forum, myself & many others have found some mistakes in Dr Ebert's book & found methods that work better for us. Although we do still refer to his book for many IDs, I think the all years of practical pufferkeeping experience combined at TPF can at times, superceed what we have read in that book.
*Edit* As I read the T lineatus profile in the Ebert book, he states this is a freshwater puffer. So I don't know where you got in his book it is BW.
We are always open to new things in the fishkeeping hobby. Good luck keeping your fahaka long term in BW/high-end BW (or at any SG for a long period off time, since a FW fish can't regulate the osmotic pressure in salty water) & even better luck keeping it in a 75g tank.