TwP,

I did an extended tang this year with some help on the planning and welding from one the guys here. The basic metal work wasn't too big a deal. Inletting the new tang was straightforward. That tit at the end was a bit ambitious. Engraving is definitely for a pro.
If you provide some more details I bet you'll get all the info you need. Gun type, does the gun need to be de-gripped, etc.

Before

After