Top end advice

These photos are of my SX200 barrel which many year ago was bored out to 225cc. It has sat in the garage for past 40 years, and now in the light of day, I'm not sure if the set up is compatible with todays scootering and fuels. It was a runner when it was dismantled! The barrel has the lower fin chipped below the exhaust port. The cylinder head has an impact area at the 8 o'clock position on photo - will this polish out? How are compression ratios these days, if I remember this was a high compression engine. Not sure how to clean the rusty areas, the bore measures 69.97mm - will linishing increase this dimension greatly?