If you are running the counter balance belt, it's still has the shafts installed. A balance shaft delete will pose no mechanical issues if done right. You will gain throttle response, remove a weak link in the oil pressure system, make the secondary counter balance timing belt redundant and take a load off the oil pump. 4G15 Lancer engines run a stubby oil pump shaft which is a crucial component for the balance shaft delete as this OEM factory shaft has an oil channel around the shaft and a through gallery (and the Mitsubishi part is CHEAP). Aftermarket kits are known to cause oil pump failures due to lack of adequate lubrication around the shaft due to the omission of the oiling channel and gallery.
Good luck with getting it running right - you are almost over the finish line