I too used seats out of a Scion TC to replace my worn-out, ratty looking bench. When I was walking through the junkyard to see what they had I was very surprised to learn most newer cars have either beige or gray interiors; surprisingly black was quite the odd ball. So luckily they had a 2004 Scion TC with black seats with blue centers, which worked for me.
I decided to use 1-1/2 square tube to make mounting points rather then cut up the floors. The driver's side was pretty straight forward and there was enough room to avoid the bench seat hump. Doing so also put the seat on center with the steering wheel.
The passenger side however had less room (about 18" vs. 20") and there was no way to avoid mounting the square tube onto the hump.
The damn hump is also on a greater angle than the rest of the floor, so I had to make up the difference between the inner seat rail and the square tube.
So the end result is that the passenger seat wound up sitting slightly higher and slightly more reclined than the driver's seat. But it's actually not noticeable at all and sitting in the seat it's still perfectly comfortable.
My costs were $70 for the seats and $16 for 4' of the 1-1/2 tube steel, a short piece of 1-1/2" x 1/8" flat steel, and some 5/16-18 fasteners to bolt the mounting tubes to the floors. And yes, I put in new front floor pans while I was at it.