Nathan,
This is going to be something that ''hopefully'' is archived on someones computer with descriptions of the unions, fittings and pipe sizes. It is highly unlikely but I will check around for you.
Unfortunately there is no going off of memory with this skimmer for anyone to even tell if it was Metric or standard PVC fittings / pipe used to complete this system.
You may want to take the skimmer to a local hardware store and see if they can offer any help in determining what size you need.
The other battle is going to be routing the plumbing as it was intended to work with needed dimensions.
One last thing is going to be the pump if it is not working you are pretty much dead in the water unless you can locate a pump online that someone is selling on Ebay.
Unfortunately this skimmer has not been in production or in our possession for 10 years or more.
None the less on tuesday when my techs get back in from the Christmas holiday I will pick their brains to see if I can come up with any information to help you.