HI Frederik,
There are a few places you can buy a suitable manifold for the for the Jenvey's for the 1.6 engine,
https://www.sp-el.cz/zavodni-sani-felicia-1-6-kitcar
The Sp-EL ones are not cheap though, but do appear to be based on the Works Kit Car spec.
These are cheaper, and offer a kit involving the TB's too:
https://dbilas-shop.com/en/intake-tract/inlet-manifold/seat/1046/intake-manifold-for-vag-1-0-1-6-8v?c=10969
https://dbilas-shop.com/en/intake-tract/throttle-body-kit/racing-version/vag/174/mutli-throttle-intake-system-for-racing-vag/seat-1-0-1-6-8v?c=10930
I'd suggest you'd also really need a stand-alone ECU to make the best of a set of ITBs on that engine, and it would be worth changing the cam too if you're going to this much trouble.
This place does a cheaper option for the AEE motor using Suzuki GSX-R throttle bodies.
https://danstengineering.co.uk/VW-Polo-14-8v-ABU-APQ-AEX-AEE-Inlet-Manifold-to-Suit-Standard-Spaced-GSXR-Throttle-Bodies
Cheers
James