Firstly, an apology that there aren’t any pics of me getting the motor in the frame. With all hands required it’s hard to take pictures. Will try so with the custom Z900 when I’m on that build.
As with most big, heavy bikes, the best way to get a motor in a Z900, during a full resto, is to lay the engine on the bench on its side using small blocks of wood to prop it up in the best position. It is imperative to protect the paintwork of the frame with soft materials that are tough enough to resist the sharp edges of the engine unit. High-density pipe lagging offers great protection and can be used in some places, but unfortunately there are plenty of vulnerable parts of the frame that need more clearance than the lardy insulation permits. Where there’s not much clearance I use bits