Why! You are already reading the PWMJ1850 network no need to go and "try to find it"!
You apparently are not understanding that your Mk 1 has no CAN bus. The PWM Network in your module tab is J1850(Ford actually calls it SCP or Standard Control Protocol. The rest of the industry calls it PWMJ1850) and your adapter is reading it just fine as well as reading the ISO network modules according to your screen shots. That is all the modules the car likely has!!!
There is likely not many options that can be changed or enabled in any of those modules
The reported Can error has nothing to do with a CAN network as this car does not have one and the HS/MScan switch is not even needed for this car!
The Can error you are receiving is a network error message that means that Forscan is having to request data multiple times(3% of the data had to be requested multiple times) Data packets from one or more modules is being received with errors or arriving with data missing but subsequent request are receiving the missing data but this error correcting is triggering this error message!
It looks, from your screen shots, like Forscan is getting an acceptable read before the modules are declared AWOL and this network error is most often a problem seen with the lower end cheap adapters!
It can also indicate one or more modules is slow in responding to data queries and had to be woken up with multiple requests before it responded and sent the data.
Again this is most likely an adapter error with slow data queries rather than car network problem even though your getting a good 3 Millisecond test response at the beginning!
This is fine if you are only checking and clearing DTC codes but a detriment for programming of any kind and it can even cause a module self test to fail before it is finished or to stop reading data and dropping out during PID reads!
Because of that error I would not be doing anything involving AsBuilt module configuration with this adapter and Forscan probably will declare it unsuitable for programming!