I'm not sure about the saves, as your actually playing BG2 game/engine with the BG1 story...so you'll be importing BG2 save into a new BG2 game....must be a way to do it.
At the very least I suppose, just start a new game and use Shadowkeeper to match your old characters stats/xp.
At the very least I suppose, just start a new game and use Shadowkeeper to match your old characters stats/xp.