Hey all , looks to be a V48 pace special 1966 - 1968 the V48 were the later model and had a long snorkel and handle mounted filter, rather than a 7j air cleaner mounted on the crankcase. looks original .
Being a pre G3 carb 125cc it should have the shorter crank shaft which means it will have a blade plate similar to the victa consul & cortina rear discharge mowers

http://www.ebay.com.au/itm/victa18-...mowerAccessories&hash=item3a7bd9f833
These blades should suit the holder however if your mower shop can get you catcher model blades for 1960 -1970 catcher models they throw better.
don't attempt to fit a 70 series plate to a short shaft 125cc motor , there isn't enough thread to accommodate the larger boss and the nut loosens and strips the thread.
hope this helps .