The body is definitely not scratchbuilt (as far as I understand the term)... but a modified production piece. Sure, it's highly modified, but you still started out with a manufactured body... and modified it. You didn't create a body by carving a buck out of a hunk of basswood and vacu-forming it out of sheet styrene, or by hammering brass or aluminum sheet to shape. To me, when someone says their model was "scratchbuilt," that means it was created from raw materials ala Gerald Wingrove. Like I said before, a model may not be entirely scratchbuilt but may have scratchbuilt components, which is what it sounds like you'll end up with.
The "misuse" of terms that I was getting at in the first place is when someone takes a body from kit A and a chassis from kit B and an engine from kit C and some spare parts and puts it all together and calls it a "scratchbuilt" model, which it isn't.