You might want to drag this question over to the Marlinowners forum.

But yes, you can convert at straight to pistol grip. It takes a replacement of the lower receiver as well.

You might be able to reshape the wood to fit on the straight frame. I haven't tried it.

There are a lot of experienced collectors over at MO. Someone there has done it.

"The greatest danger to American freedom is a government that ignores the Constitution."
Thomas Jefferson