Help with throttle body

I'm planning on fitting a MK2 Golf Gti throttle body on my MK1 1800 k-jet Golf. Apparently it just bolts straight onto my intake manifold. Can anyone tell me how to port my intake manifold?

I've got a 2e in mine and ported the manifold while it was off the car. I just bought a Mk2 gasket, placed it over the manifold, marked around it and then filed the manifold to fit. It does get pretty thin but it's OK. Cheers.