That's a good request. I've seen some great photo sets in the Library of Congress archives. I'll see what I can dig up.
These photos are pretty outstanding as well. Sourse NASA Altitude Wind Tunnel & Space Power Chamber Galleries archives.

Boeing B-29

Boeing XB-29-BO (SN 41-002, the first XB-29 built). (U.S. Air Force photo)

B-29 arrives in Cleveland as part of the Aircraft Engine Research Lab's intensive study of its Wright R-3350 engines

B-29 arrives in Cleveland as part of the Aircraft Engine Research Lab's intensive study of its Wright R-3350 engines


AUXILIARY COOLING DUCTS ON B-29

AUXILIARY COOLING DUCTS ON B-29

B-29's Wright R-3350 Engine Nacelle in Altitude Wind Tunnel Shop

B-29's Wright R-3350 Engine Nacelle in Altitude Wind Tunnel Shop

B-29's Wright R-3350 Engine Nacelle in Altitude Wind Tunnel Shop

Cowl for B-29's Wright R-3350 Engine in Altitude Wind Tunnel Shop

Front View of Wright R-3350 Engine

Wright R-3350 Engine for B-29 in Altitude Wind Tunnel

Wright R-3350 Engine for B-29 in Altitude Wind Tunnel

Wright R-3350 Engine for B-29 in Altitude Wind Tunnel

Wright R-3350 Engine for B-29 in Altitude Wind Tunnel

Fuel Injection Manifold on Wright R-3350 in Altitude Wind Tunnel

Front View of Wright R-3350 Engine