Nick if you dont want to race it in the under 2ltr class just stick to an Mr20 the 1188cc motor in all alloy is quite a challenge hence I suggest the ma12s then you can just use thicker cylinder liners and only 8v to play with. It will make hp with the right small roller bearing turbo. There was a guy in queensland making over 250hp ATW with a 1200 cc or less suzuki gti motor and with a small turbo that was supposed to max out at 11psi but taking it to 25psi with no issues.
Keep it simple

For all others considering a bike motor dont forget to have a minimum of 5kAUD for starters just for a decent r1 or 1300cc bike motor. Then another 10k to get it fitted and going.