Small displacement engines are easy to over cam because they make camshafts behave like they are bigger (duration) than they are. On your 344 I personally wouldn't go over 264@050 (and that is if you are indeed 13:1 static CR) but I'm sure others will recommend otherwise. As far as lift, having your heads tested on a flow bench will be a valuable tool, it will also help spec how fast of a rate of lift. Best bet would be to call someone like Bullet cams with all your accurate specs and they will help you out.