I understand your reasoning for wanting this particular FB, since he will trade apparently.
But after having L O T S of experience with these, for a 350/v8 swap you should really look into finding a GSL limited slip rear end, with the disc brakes.
Regardless, those will have to be changed/modified.
And it'd almost be a shame to get rid of a sub 95,000 mile 12a. Those little motors are literally known for going a million miles.
In my humble opinion. In regards to this car.
If you want a v8 swap. Find a beat GSL, youre going to have to take/cut either vehicle apart anyway, so why not start with something a little less complete. And it will also make it a lot easier cutting into something that didnt look pretty to begin with.
Personally, Id trade the civic (if youre down to lose 20mpg instantly) for this, then drive the hell out of it as is.
Youve never even driven the car yet. Dont swap stuff till you know what the car is like, you may actually love it in stock form.
My unimprsssive 2 cents....