What an elegant engine! It looks like a standard Porter Class B-4-T 4-4-0. My copy of the 12th edition of the Porter catalog says, "Class B-4-T is designed for speed and long runs; sixty miles per hour or more is practicable; it is easy on the track and curves well."
The B-4-T was offered in several standard sizes: 13 x18 with 48" drivers (code name "Hagnon"); 14 x 20 with 50" drivers (code name "Hakkoi"); 16 x 24 with 56" drivers (code name "Hakzig"); 17 x 24 with 62" drivers (code name "Halban"); and 18 x 24 with 62" drivers (code name "Halced"). If I just knew the cylinder and driver dimensions then I could give you everything else, assuming the railroad opted for one of the standard models when they purchased the locomotive.
-Philip Marshall