completely cutting out the floors and having other sheetmetal replacing it.

good or bad for the unibody and can it get messed up?

Yes and No.

If you leave the trans tunnel, the rocker panels, both inner and outer intact and they haven't been weakened, then you should be ok. But if they're not in good shape, then you can weaken it a bit.

By the way, you can get replacement floor pans from Charlie Osborne at Zedd Findings and they're virtually identical to the original floor. If you get a good qualified welder to install them for you, you'll actually strengthen your floor.

2¢

this is for my 510... I'm working on getting a 240 after this is running

Give charlie osborne a e- mail and see if he has what you need. I am ordering a set of floor pans for my 240 Monday. :classic: Zedd Findings carry a lot of stuff not just floor pans. datsunzparts.com