if its got 192K on it and it has already been bombed then i wouldn't worry about the 53 block. mine is a 53 and has never given me any problem. the majority of the ones that were a problem (a very small % of the 53's) generally showed their issues between 60-90k on the odometer. if its gone 12 years and almost 200k with no issue then there is no reason to think that it is going to magically malfunction now.

sounds like a good truck overall, i would concentrate my efforts on the front end. check the tie-rods, ball joints, wheel bearings, steering gear, trac-Bar and shocks.