The idea of integeral scope mounting built into the action was used but the mass market, namely America, didn't like it so it was dropped in favour of bolt/screw on bases.
The Parker-Hales being a Mauser 98 action in most cases has a really wide selection of bases and mounts to choose from only really limited by you budget.
I have a set of Apel Roll Off mounts fitted to my p-H 1100 Lwt. One the 1200C it came with Leupold Std mount on a one piece base what some one referred to as the Windage adjustable type. In fact they are of Redfield Junior design

. The 1100M has Weaver bases and mounts fitted and the 1200 Super in 7.92mm has Leupold Q/R level operated mounts fitted, the rest have Parker-Hale bases and mounts.
Personally I do not like the Weaver ones and not really enamoured with the Std Leupold mounts. The lever ones work well.
The problems really start when one tries to fit hubble sized optics with 30mm and plus tubes. I have found that staying with traditional normal objective sizes and with 1", 26mm and even 30 mm tubes simplify scope fitting:-
That is a 30mm tubed Tasco Titan 3-9x42 in p-H mounts.
This is a P-H 1000 in .243 fitted with an 8x56 1" tubed scope in P-H RAHS.3 rings on std P-H bases.
It fits with clearance as you can see, no it's not one of mine

, just shows that scope fitting is not really the problem some think on these old rifles. The RAHS.3 rings are getting harder to find now of course but are only really required with objectives larger that 45mm.