The Breva 750s have plastic (Nylon) fuel tanks that are affected negatively by ethanol fuels. The alcohol or water that the alcohol attracts damages the Nylon, causing it to expand if used for long periods or in the likely case of the Breva 750 under discussion, to have been stored for years with ethanol fuel in the tank. One effect is to cause the tank to swell in such a way as to make re-fitment on the frame a bit of bother.
Pure Gas sponsors a website showing all the gas stations in the USA and Canada that sell various grades (octane) of non-ethanol fuels. My '04 Breva 750 has never been stored with ethanol gas and its former owners apparently were also very fussy about that. Texas has many gas stations that sell non-ethanol fuel. One is less than 3 miles from my home near Austin. 90 octane non-ethanol fuel is about $3.79 a gallon today.
As to what to do with this bike, does it start and run? If not, your friend can avoid it or bid it down significantly based now on your knowledge of the effects of ethanol fuel. If it's sat too long, the injectors likely are blocked with gelled gasoline
I'd offer $1500 for it.