Yes, a ULE will fit a classic Mag.
The first upgrade you'll want to do is a better barrel. That SP progressive isn't a smart choice. Something like an All American would do nicely. Barrel kits though are much much better.
It already has a level 10 from what i saw on the sale. So next would be trigger frame. Either a logic or intelli frame. IMO logic's look much much better. Though i ended up with an intelli, go figure. You'll find the benchy frame that is on there to be way too slow, though the pull is smooth and sexy
Big upgrade would be X-Valve or Retro Valve. Kinda pricy, but DEFINITELY worth it.
Good luck! Anymore questions feel free to ask.
- Brian