Hi, I like your thinking. You will want a good 16valve head with light valves etc. You will need a lot of valve area so you don't need to run much camshaft. Something with a very short stroke and large bore. Most OEM engines are not designed like this. Unfortunately utes are not allowed in IP.

Edit: that being said, you could run an 8 valve and small turbo. But you will never get near the choke point of the restrictor, And would be limited by rpm. It would get you out there but would not be competitive with good NA 1600's. They make 130Kw + atw.

To fit a turbo that could max out the restrictors capacity. A 930cc engine wouldn't make boost until 6400rpm. Peak Tq would be around 8000 and peak HP would be closer to 10,500. It would be running about 40Psi. You would need to design an engine around this, keeping in mind that you can't have overlap on the camshafts. It's a challenging design brief, but possible.