The warco is called WMT300 now do not know if the 300 is smaller than a Clarke 500 or just badge engineering ?
However measured one up tonight and the 70 tooth is 72mm OD so definitly 1 MOD.

The gears on this one have 4 splines on a 15mm shaft.

And the milling head I'm guessing at 1.5 MOD 45 teeth mitre gear, this machine doesn't have a milling head, been removed, so can't measure the mating gear and this one is hard to measure without a strip down.
So we need some information from James before anything else can be worked out.
Are they 1 MOD ? Need to numberof teeth and the OD of the only existing gear
And what is the fitting ? Even if the spindles are missing the end of the leadscrew will give this information as the same gears have to fit this.
As has been remarked earlier ARC sells a metal gear set for the C3 at about £58 and by the time you take buying gear cutters, messing about, blanks etc to me it's a no brainer to use chequebook engineering.