I have begun a remodeling project and removed a wall and two closets in
preparation of enlarging the master bedroom. THe floors are typical mid 60s
oak hardwood floor planks 5/8" x 3" or so (I think) Anyway the places where
the walls were removed have no flooring and I must patch in between with
same floor boards salvaged from a foyer tiling project earlier in the year.

The problem is that the salvaged boards have the original nails in them
which are set, patched and varnished over on the top and sticking out the
unfinished bottom. If I try to nail the board as is or remove the nails the
board splinters at the head and will require repatching eventually.

The advice seek is: Would it be better to just push the nails out, flip the
board over (unfinished side up) and then nail it with fresh nails in the old
holes. I do plan to sand and refinish the whole floor. Will this cause a
color variation in the patched areas. Should I stick to installing them
finished side up? I could also clip the nails and use adhesive to put them
down. Has anyone done this? What were your experiences? What method works?