How would I convert a wood burning fireplace to gas?
The plumbing is not that hard, but you'll need a new fireplace and a new stove.

See if it's legal to use flexible corrugated line where you live. It's covered in a yellow plastic jacket. Corrugated Stainless Steel Tubing (CSST).

It'll be MUCH easier to install, plus under a house where there is moisture it'll hold up better.