There is an interesting report by the US Office of Naval Intelligence on the Battle of the River Plate, with quite a few photos and ship damage reports. It can be found here, at the Combined Arms Research Library Digital Library, and downloaded for free.
http://cgsc.contentdm.oclc.org
As for a battle between the Admiral Scheer and a Baltimore–class cruiser, I would bet on the Baltimore-class ship, unless the Scheer got some early lucky hits on gun turrets, as the Spee did on the HMS Exeter. The USS Salt Lake City, one of our two oldest heavy cruisers in World War 2, with an older gunfire control system than the Baltimores, was able to score hits on the IJN Nachi at ranges in excess of 21,000 yards. The following comment from the ONI report applies to the Spee’s gunnery.
German shooting was described as quite good, initially, but the accuracy fell off rapidly.
(a) 11-inch opened with two 3-gun salvos, very close and on in deflection.
(b) 5.9-inch also fired at Exeter; no definite hits determined, but many splinters came aboard.
