fabled kz750b cam mod

Ok have 79 kz750 twin down alot mods so far intake exhaust gearing ECT. I'm now to the point I need to do the fabled dual exhaust cam mod to get my top end up to par. I know it is possible to replace the intake cam with an exhaust cam by cutting off the gear for the rpm tach. Does any one know how to go a bout the timing marks on the cam gears. Do I swap the the intake gear to the new exhaust cam or are the interchangeable