Scaledecks might the company you are thinking of. They have 2 different Titanic pre-cut decking sets. One has the cut-outs for things like the vents and the other is uncut so the modeler has the option of doing the corrections to the vent placement and benches.
Below is a link to a build where the modeler used Scaledecks' "Tinted Wood" in uncut sheets. About 1/4 of the way down the page, you get a picture of the decking.....so you can get a pretty good idea of what the product looks like. If you scroll down to about halfway, he mentions the type and color of the material.
titanic-model.com/.../dcboard.php
I hope the link works for you. That 1/350 Lusitania turns into one beautiful ship. I'd love to do one but I'm running short on theoretical shelf space.....and then there's the price. Not an easy kit to find that's NOT at least a hundred dolars or so.
On that site, there is a Lusitania that was just finished and photos posted. Maybe you can draw some inspiration there....or from some of the other Lusitania builds that can be found in the "Posted Models" section.
Would love to see photos of the build.....or at least finished photos (when that day finally comes).
Matt