It only becomes prohib if you cut the barrel of a restricted.
If it is non restricted as long as you stay over 18.5 inch it is still non restricted but if you go shorter it becomes restricted.
The rules are really stupid. I can buy a 16 inch barrel AR then replace the barrel with a 10.5 inch barrel and it is still restricted but if I cut that 16 inch barrel to 10.5 inch then it is prohibited. Make sense? Not to me either.
Like I said earlier, to me it looks like you will lose $800 if you buy the parts and repair it then sell it or if you just cut your losses and sell it for parts now. To me I have better things to do with my time than chase after parts and then try to sell a rifle unless I was going to at least lose less money that the other option.
I guess it doesn't hurt to wait to see what they are going to charge you for parts though.