Sporterizing, Bubbafication, and Rebuilding are three separate things in my opinion
Re: Sporterizing and Bubbafication, Bubba doesn't just dabble in firearms. He's been around a long time, hacking up collector cars. Bubba is a shadetree mechanic with more ambition than skill, his standards fall under the 'looks good from my house' category, and his main tools are a hacksaw, dremel, and sledge. When Bubba pop rivets on body panels, he's hamfisted at that.
With firearms, Bubba like to hacksaw barrels short, can't strip a pistol without the aid of a dremel with the wrong stone in it, and cold blue without the benefit of a good cleaning first is his signature. He'll add the trigger cutouts on your 1911 frame with a rat-tail file and he'll put a thumb-hole in a rifle stock with a vise and a hand-drill- hey, those visejaw-marks on the stock are character-marks. He's sloppy, imprecise, and unconcerned with almost anything except solving whatever 'problem' he's trying to address with as little expenditure of effort as is possible.
Sporterizing can range in quality and effectiveness from "amateur" to "stunning". Bubba might say he sporterized a rifle, but he's using flowery prose to hide the file marks on the barrel and the re-crown job he did with wood working tools he found in the barn.
Rebuilding is entirely another thing. A rebuild may have "non-matching" numbers. Then again, during active military service, the rifle may have been "non-matching" in regards to numbers for almost its entire military career. And of course with certain firearms, "the numbers" never "matched" on the day they were made. And on the other hand, a rebuild may include completely correct parts from tip to toe