undercar appearance questions

I recently finished replacing my floor pans and sealing up the floor in my 70 nova. My question is you can still tell I replaced the floor pans from underneath, you can still see the lines where the old meets the new. So can I bondo over this to smooth it out or will bondo crack and fall off. or does anyone have any other suggestions. It would be greatly appreciated.

Thanks

Not sure on the bondo, but you could try spraying the underside of the car with rbberized undercoating spray. It should cover your seam nicely, plus it's not a bad sound dampener either.