81' KZ1000J rebuild

My dad has a 1981 KZ1000LTD with a CSR engine (has mech. tach output). It has a mildly blown head gasket on the left side (cylinders 1 and 2) but it still ran pretty good and had alot of power. He told me to tear it down and put it together and figure out what we need to buy. I know that guy likes going fast but he also enjoys good gas mileage and cruising around town. The stock pistons look alright (somes marks on the sides but i can't feel them with my finger nail) and the cylinders looked good too. So i could just get rings and throw it back together. But what im wondering is if theres any noticeable increase in power when you go from stock displacement to the wiseco big bore kit (stock sleeves). no porting or big valves either. stock BS34 carbs. Stock exhaust. Just bigger bore. Is it worth it?

Thanks guys,
KT

You will get a bit more Ooomph if the Wiseco's are the 10.25 to 1 ones and not stock compression.

Yep it'd be the 10.25:1 kit. Would it still run good on normal pump gas too? Like 89 super unleaded?

Yes! mine do.