Without more information about the condition of this piano I can
only conjecture, so here goes.  To begin with I'd check with another
tuner if one is available to see just how bad the pin-block
(wrest-plank) is, to determine if a pin-block treatment would be
effective.

If it looks like a pin-block treatment would do some good I'd have
that done before anything else.  An upright piano (vertical) will
require that it be laid in a horizontal position for several days;
I usually figure on a minimum of ten days for a thorough treatment.

After the pin-block treatment the pin should be again tried for
tightness to see if it will hold pitch.  Usually this will prove
successful unless the piano has had some really bad treatment.

Presuming that the pins will now hold fairly well better than before
the treatment, it might be worthwhile to tap the pins in to make them
slightly tighter before tuning.  In the case where there are still
some pins that won't hold pitch pin shims may be used.

In any case set the piano back to its normal position for several
days prior to tuning to allow it to adjust its internal pressures.
It may even require several tunings to bring it up to where it is
satisfactory.

Also, remember that pianos made before about 1918 may be designed
to be tuned to a lower pitch, below A=440 Hz.  This may be anywhere
between 428 Hz up to 440 Hz.  Hope this helps.  Good luck.

Hal Davis