The MSM80C154S/MSM83C154S port operation instructions for ports 0, 1, 2, and 3 are divided into two groups-one where external signals applied to the port pin are used according to the instruction to be used, and the other where port latch data uneffected by the external signals is used. Instructions which use port latch data are listed below:

INC data address
DEC data address
ORL data address, # data
ANL data address, # data
XRL data address, # data
ORL data address, A
ANL data address, A
XRL data address, A
CPL bit address
JBC bit address, code address
DJNZ data address, code address
PUSH data address

so a simple
PUSH Port
POP ACC
should do the job, without intermediate change of values.

I assume that this applies to all 8051 derivatives, not
only the MSM80C154S.