first off, are you using dowels for foreshafts or nocks? if using for foreshafts, then the joint is suppose to be the weak spot. most people getting into making cane arrows don't understand that the foreshaft is suppose to break off after impact to save the main shaft. "primitive man" figured this out and the reason, it's easier to find a straight piece of wood that is 4" long rather than 28" long. using foreshafted arrows have saved me countless hours of remaking cane shafts that would have been broken had the arrow been a simple shafted arrow. foreshafted arrows DO NOT like glancing blows, they will snap. as they are suppose to. i bounced a foreshafted arrow off a tree one time at a 3d target. the foreshaft stuck in the target but the mainshaft went on its own journey. but to answer your question, the taper method is the best of the two methods of attaching nocks or foreshafts.
to answer your second question. if your bow is 60#, then the stiffest side of your shaft should be 60# and against the shelf so the arrow can deal with the paradoxing . that is if your shooting a 28" shaft and a 125gr. point. if you're using 80# spined arrows, then you need to be shooting 225-250gr point with a 28" shaft. of course, you have to adjust spine for the amount of taper your cane has. if not using this weight point, then chances are your 80# arrows will hit way left. my formula for calculating arrow spine to too complicated to type, but it's usally dead on. hope all this helps.