I'd guess H grade also.
I just sold a H 16ga and have a GE in same # range and the G's usually have some engraving on the bottom and top of the frame as well as the sideplates. I have a 6x,xxx range straight grip gun with the long trigger guard tang. I guess there could be original straight gripped guns with the short tangs but I don't see why the factory would have sent them out that way. The wood sure is mismatched in condition and color.

I agree with KY maybe $1500 to $2000 if it is original and was all cleaned up with no barrel problems.The 16ga. Lefevers are great handling guns and fairly scarce.
Good luck,

Fritz