Yes, the F54N is a 1954 261 made in Flint, MI and originally installed in a 1954 6000 series (as the HD Jobmaster optional engine).

Someone else will have to help you with the rear axle serial number 5800 M 429 2 Y
http://chevy.oldcarmanualproject.com/chevyresto/54057.htm

What year truck body is this (is there an ID plate, with the vehicle serial number, in the driver's door jamb)?

Tim
1954Advance-Design.com
1954 3106 Carryall Suburban
1954 3104 5-window pickup w/Hydra-Matic
The 216 and early 235 engines are not "splash oilers" -- this is a splash oiler.