Cx650 smoking at mid throttle once warm

Hi All. Some general consensus advice would be appreciated. Just rebuilt a basket case 650ED Eurosport. Just passed her UK MOT and no issues at all. Other than I have noticed that once fully warm she puffs out grey smoke after 5k rpm which smells acrid enough to be burning oil. Not noticed oil level dropping but only done about 30mlies on her. It is a donor motor that had sit about for a bunch of years that has been fully stripped and rebuilt except crank and pistons but all other parts have been out and replaced, cleaned, bypassed, etc. Only thing I did not do was pull the heads and pistons as she had good compressions and ran ok on the bench.
Carbs have been fully ultrasonic cleaned and fully rebuilt. All jets and emulsion tubes are new only original part is main needle as they are often not good in rebuild kits to my view. No smoke at idle and low speed and she starts and runs sweet as a nut every time and drives just fine with good power. Compressions are both 170. To my view it’s an oil control ring problem and I have a set of new standard rings to hand as I am just that sort of obsessive!😳. Would the populous agree she needs a re ring or am I missing something obvious and going for the nuclear option? All opinions and experience appreciated.l