That's unusual. Usually you would fix an idling problem with the motor installed so you can adjust it while it runs.
Do you have a digital camera? That way you could take a picture of the motor so we could verify the induction setup.
The 2.7RS is a great motor. Arguably one of Porsches best. If a search doesn't turn up the original car then just install it and enjoy. It'll be a blast.
Here's some photos of the different inductions. Yours should look like the first photo. A 2.7RS.
The second photo is a 67'S with carbs.(thanks Shawn
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