How hard are the floor pans to replace?

I just started to gut the interior on my 70' Nova and although I knew the floors were horrible on the drivers side I found some thin spots on the passenger side as well as a few holes. All the rot is in the lower pan areas of the front and rear seating areas but the area under the front seat is fine. Is it easier to just replace the 4 smaller sections or just to buy both the left and right side complete floor pan? Is this a job that is easily done or a job left to the professionals? There is also some rot in the area to the left of the brake pedal on the firewall riser. Is there a replacement panel for that area or is that something that will have to be prefabed?

Thanks

Gary

if you dont feel comfortable with doing this DONT DO IT youll get futrated and give up with somthing worse that with what you started with but remember if you do this DONT cut the floor braces just the floor