I am using a floor mounted peddle box and yes you may need to modify/strengthen the mounting area/floor pan for obvious reasons.

Seating position may influence your choice, with a bulk head box you push down and forward on the peddle where a floor mounted you just push forward this suits a lower seated position where your legs straighter.

Its abit like driving a BMW with there different style throttle peddle set up.

What ever you do don't use a OBP box there total crap.