As for "clutch holders".. I have a simple tool.. Remove the plug, use a length of nylon rope that will fit into the plug hole. Put in about 4 or 5 inches of rope, making sure that you have a good bit out of the hole so you can remove it.. Mine is about a foot long.
then rotate the engine around until the piston hits against the rope. The engine won't turn, and the rope won't do any damage. Sort of like that nylon stopper that Motion Pro sells, only cheaper.
And don't use an impact on your clutch springs when installing.. As a matter of fact, don't use a lot of force to tighten them. They break easy..