Leave it as is and sell it on gassavers web site where it will be bought by someone who will appreciate the mods. Seriously I think I would first advertise it as a car modified for FE sold as is. If you didn't get any takers you could always remove the mods and sell it as an original stock car.
I don't think the average used car buyer would notice any of your mods anyway. Things like LLR tires, grill block, WAI, even the Z1 in my 90 hatch would go unnoticed even my most mechanics unless they were Honda specialists. Unless you've done some extreme "backyard mods", particularly some of the aero stuff I've seen, nobody will notice.
Highway mileage should be near 30, so I'm betting if you drove it highway, you could take it to 35 w/ some careful driving.
My Z28 before mods was getting 28 and 29mpg highway, now w/ tuning, full exhaust, gears, and pushing 18" wheels w/ 315 rubber around, it's lucky to get over 20 highway.
My 99 3.8L Firebird Convt. got 31-32 out on the road stock. It had the Y87 package, which included a 3.23 rear and torsen posi unit. My 98 Trans Am Convt. gets 28 out on the road doing about 70, 17 best around town.
The airbox and scangage will go directly into an SC1 with minimum effort. Same parts.