Correct coil for mk2 1.05 hz engine fitted to a mk1

I have VW golf mk1 with a mk2 1.05 hz engine fitted and have worked out (with the help of Google) that my idle shut off valve/solenoid (at the moment disconnected) has its power supply from the +15 part on the coil.
The thing I need to ask is the car has the original coil fitted with just the 2 terminals either side  whereas the coil that seems to be the correct one for the engine is a later version that has 3 on one side and 2 on the other and different part number.
The car starts first time and runs ok aside from no idle without the choke on would the older type coil cause an issue with the idle/running and would it need the later correct coil.