My father sold his 1966 Porsche 912, and the person that bought it is having it transported to them. The problem is that the car needs to be running in order to load it on the truck.

The engine has been rebuilt and yes it does start. We had it started and running a while ago (4 months ish) but since then it hasn't turned over. Sometimes it gets close but to no avail. And yes it has gas, oil, etc. It is a dual carbureted 4 cyl. Anyone who knows anything about Porsche or VW engines should be able to help out hopefully.

No one in the family is a mechanic by any means but we just need enough to get the car running enough to get it on and off the truck. My father thinks it's a fuel flow problem. When we initially got it running, one of the carburetors was making like a choking sound (don't really know how to explain it) like it wasn't getting the proper air to fuel ratio. We have been told that there are screws that can adjust that but we haven't been able to figure anything out.

I know this might be a long shot, but we need it to start so any advice would be helpful.

This is the only picture of the engine I have at the moment.
Engine