Update. Talked to local dealer and he said saylor beal has threaded head where the intake goes into and i sent a pic to him and he said never seen that before. Any saylor beal guru's on here can help? Love this place.
You've an older pattern of Saylor-Beall pump.
Several of the older 703 and 705 S-B pumps I've worked on have both the pair of tapped holes for the earlier style filter and a pipe-tapped 'NPT' hole for the later style.
If yours lacks the pipe-tapped hole, then just make up an 'adapter', a rectangle of steel flat, say, 3/4" or so thick, drilled to match the tapped holes in the head, and tapped 3/4 or 1" NPT to accept a later style filter.
(edited.....if you haven't a suitable pipe tap, just drill the adapter plate, and weld or braze on a pipe coupling to provide the NPT tapped hole.)
Obviously, be certain that the adapter is correctly flat to fit the head, and make up a, say, 1/32 or 1/16" thick paper gasket to seal up the fit.
Compressor filters with a pipe thread mounting are 'generic', so one of any good make will filter the air for your pump adequately.
cheers
Carla