Jim,
I canibalized my Trix 2-10-0 for parts (i.e., the boiler and tender shells)... Max Magliaro is the guy who recently did a 3-part story in Railroad Model Craftsman on building a PRR Class I1sa 2-10-0 in N scale. He essentially extended a Kato 2-8-2 by adding a 5th driver and extended side rods. He then used the GHQ L1s 2-8-2 pewter boiler conversion kit.
The Trix 2-10-0 should handle 11" radius curves. If I remember correctly, there's plenty of side-play in the mdidle drivers. I don't recall, but it might even have a blind center driver (like the real PRR I1 class).
A few minor points to bear in mind with your 2-10-0. The drivers are undersized (in part because of the deep flanges that require Code 70 track or higher) and the cylinders don't line up with the steam pipes. This is because the mechanism was made for a German loco and they simply placed the K4 boiler on it to make the I1.
I found that out-of-the-box the running quality was kind of poor, mainly due to the electrical contacts (or lack thereof). Cleaning up the contact wipers and making sure they touch the wheels and axles will help greatly.
Overall, though, out of the box it looks quite Pennsy.
Now, you can get an even more accurate looking I1 if you shorten the boiler a bit behind the smokebox so the steam pipes line up with the cylinders. Also, the bell and dome need to be swapped (that's not so easy, but also not impossible). The tender can be used as-is, although it's technically a passenger tender (PRR class 90P75, IIRC), but photographic evidence suggests 90P75 and similar 90F82 class tenders made it to the back end of I1s from time to time.
Good luck, and welcome to N scale PRR steam!
EDIT: Oh, yeah... My minimum radius is 13.5". My M1 will not handle that. It stays on my outside main at 15". I don't like that, but I'm limited by the 4-8-2's rather picky lack of side-play and my own choice of drawbar configuration.
The current layout is a "placeholder" until I have the room to build a much bigger Pennsy. At that time I plan for an 18" minimum radius, freeing up the M1 to handle any track.