Kirkland's book on the subject doesn't mention the fate of the 408 engines used in the prototype, but you'd have to imagine that they were scrapped, since the War was still ongoing. These were originally to be made as model 12LV, with 8"x8" cylinders in V-12 arrangement rated 500 BHP. The design was altered to 9.5"x9.5" V-8, originally 700 BHP and later 750 BHP as model 408. Kirlkand mentions at least 9 assigned serial numbers for 408 engines, and two for 12LV engines. The 12LV apparently was briefly referred to as the 300 series before being dropped. Some of the engines were earmarked for an unbuilt switcher prototype.
I have read of Baldwin having tried an opposed piston engine, supposedly the 500 series, but have no further details. I am fairly sure one of these is in Alvin Staufer's book on the Pennsy's steam, diesel and electric power. One wonders whether this would have been the original Oechelhauser patent, with single crankshaft at the bottom, or of the Junkers pattern (of which the Faribanks-Morse is a variant) with two crankshafts.
Notable but never mentioned is the fact that there are numerous subvariants of not only the VO engine, but also of the 600 series engines as well. Very much press has been given to such changes in EMD engines, for example the changes made when 567C replaced 567B, but this is rarely discussed in detail for Baldwin engines. Also rarely mentioned is the change in the rating system from a BHP rating to HP for traction in 1951, as another example.
Small, but notable as another prime mover in Baldwins is the Maybach MD655 used in the diesel-hydraulic RP210 units. Again, one wonders if, had these been successful, Baldwin would have undertaken license production of the engine here in the US. This was attempted in Britain with disastrous results; the license-built M.A.N. engines there fared no better.
It would be possible to write yet another book on the subject using various manuals and original information which has not yet appeared in print in the railfan press. It seems, however unfortunately, though, that very highly technical material as regards inner workings doesn't "do well" today in a sales sense.