In the long haul I think you would be best to stay with the water based poly. You can't really change the appearance by putting oil based poly over water based. The wood is already sealed and you would have to strip the finish off to have the grain pop with the oil based. Then oil based poly is really not a good product over light colored wood. Yes it has a amber color to it but it will get more and more yellow over time. If you were starting with new wood, then you could coat the wood with linseed oil to make the grain pop and then coat with the water based poly for a protective coating.
Without stripping the woodwork you could scuff the surface and spray some aniline dye over the finish to give it some golden oak color and then put another coat of water based poly over it.
A lot would depend on your nail gun if 18ga would work. A lot guns won't set the nails in oak and you would have to go back over it with a nail set making a 15ga or bigger size hole.
Without stripping the woodwork you could scuff the surface and spray some aniline dye over the finish to give it some golden oak color and then put another coat of water based poly over it.
A lot would depend on your nail gun if 18ga would work. A lot guns won't set the nails in oak and you would have to go back over it with a nail set making a 15ga or bigger size hole.