RE: Welcome to Club SAITO !
Unless you ensure that the crank and/or cam gear has not and will not move during the dissembly process, You will need to time the cam gear with the piston at TDC. Someone else can help you there as the procedure varies with the engine size. If you, and you might, need to remove the cam housing, make sure that the gasket is in place between the cam housing and the crankcase, as this sets the clearances between the gears of the crank and the cam. Unless the gasket is damaged there is no need to replace that gasket as it is not under any pressure (since the crankcase is vented). For the 180 I have, it was necessary to grind down the supplied hex wrench to allow it to be fully seated in the cylinder hold down bolts. Otherwise you risk damagiing the internal hex of those bolts.