I would do 10gal personally. Check out some threads on sccoa.com, there are a few that have converted to fuel cell. I know I'm going to have to address my fuel tank soon and have also been shopping for cells.
I thought about a 10 as well.. Theyre not really that expensive..but idk about pump setups for fuel cells... This car will be caged harnessed and all that.. Will have a really nice "racecar" theme going on w it.. And itll just add to it..
Hell when I scatter this SC motor I'm probably going to just 4 valve swap the car anyway..and then I will have a racecar on my hands!