I have a couple LTRs. For one I used a 10/22-T as a base model, which has a 18" bull barrel - it gave me more weight and a bigger stock & barrel, which is far more comfortable for me to shoot. On my other I left the carbine barrel, but I put a Tapco collapsible stock on it, which has the pistol grip.
There are so many accessories for the 10/22 out there, you can do pretty much anything you want. There's even a couple companies that makes a 10/22 stock set that's nearly identical to the AR-15/M16. I don't remember who they were, and IIRC, they were expensive, but I'm sure someone will speak up.
Bottom line is that the 10/22 is like the Honda Civic of rifles - you can easily customize almost every part and make it look like anything you want. But if you're really hard up for an AR-15/M16 feel, get a .22LR upper from Spike Tactical.