Very Old Intruder alarm

Hi All
I have recently moved into a new home which has an old alarm system fitted. The panel is a key operated Racal-Guardian Rascal W-71875 which is not working correctly, the front panel was hanging off due to the fixing screw posts being broken. I have decided to fit a new panel and have bought a Texecom Veritas R8 with a remote keypad. The problem I have is as follows.
As I say the system consists of the above racal panel and three PIR's One in the Living room which I am assuming is the entry and exit trigger. one in the Kitchen and one on the upstairs landing, and an external sounder.

I have traced the wiring to the two downstairs PIR's and they are wired in the normal way.

Red +, Black -, Blue/yellow Zone and Green/White Tamper

My probem arises with the upstairs PIR and Ext Sounder There is only one cable coming from upstairs and the PIR and Sounder are linked together by this cable. connected as follows

Red + on Panel to PIR and Sounder
Black H on panel to PIR and Sounder
Brown/Orange from Zone on panel to Blue/Yellow zone on PIR

Green ST on Panel to Sounder
Blue S on Panel top Sounder
Yellow Tamper on Panel to Sounder

Green from PIR to White on Sounder (assuming this to be part of the tamper circuit)
White on PIR to Tamper on Panel

I am planning on adding a couple of Magnetic contacts to front and rear doors as Zone One using them as the entry and exits and then connect the existing PIRs as zones. Also fitting a new Sounder probably a Texecom compatible with the Panel.

My question is am I Ok to connect the cables and zones as they are currently or would I be better running a new 6 way cable for either the PIR or Sounder and using the existing cable for one or the other, as I am not entirely sure about the way it is currently wired.

Also can anyone provide an installation manual for the Racal panel that explains what everything is and does. (Long shot I guess)

Sorry for the length of this post but was difficult to explain.

Many thanks in anticipation.

To be honest if i were you , mount a new sounder and door contacts , rip out the cable going to the bell and pir - put in your own new seperate cables. This makes fault finding allot easier. Wire up the bell and pir on the own seperate cables , and and also run cables to and wire them up to the new dOor contact. Stick In your veritas and wire up .

Done

Madman41
Thanks for the good advice more or less what I thought someone would say, so thats what I shall do.Just need to order a new sounder as already got the contacts in anticpation.

Cheers

If going for a texecom odyssey sounder watch out fot the "e" economy versions , as they have only 1 piezo sounder in. Go for the normal one it has 2 piezos in , batting out around 116db , it may be a couple quid dearer but everyone is going to know your alarms going off . Go on brewtimeonline.co.uk great site .