Search the forums, there is a thread specifically for it where a guy has repositioned the seat belts closer to the back seats. I think it is actually in the FAQ sticky up top.
also, I found it was a lot easier to just pick up coupe doors because the coup door panels did not fit properly on my convertible doors even with brackets cut off properly.
I had to drill about 3-4 additional holes and after fitment was still not correct on the passenger, I just picked up two coupe doors with power window insides, etc, and power door panels and put those on. It only cost me 100$ for both doors and panels but the hardest part was waiting for a deal like that. Patience man.
Also, if you search, I have a thread posted of what the insides of my convertible doors with panels and appropriate parts cut off. Look for topics created by me.
Found it for you:
zerothread?id=293193
Scroll down a bit, you will see my passenger and drivers side door frames. After comparing them side by side with my new coupe doors, for 100$ I don't feel bad scrapping my old doors.