It is hard to say without knowing what your struts are made of and how thick they are.  The bushing is not necessary for a bearign surface and rotational movement as there should not be any....however if your struts are narrow metal strapping they may not adequately take up the space that the shocks used to and the strut may move back and forth on the top mounts.....and bottom bolts if you left them the stock length.

That sounds like plenty of bearing area......however you should provide washers or spacers to take up any movement and allow the nuts and bolts to become tight on the struts.

Be aware that without any suspension the loads on the frame and mounting bolts will be increased dramatically when you hit a big pothole.  The impact will be absorbed into the tire first, then whatever is left over will go into the rear wheel, swing arm, struts and frame.  If you don't have a sprung seat.....then the impact will also be transferred into your spine.

The good news is that you can easily put the shocks back on if you hate the rough ride!

Also be aware that rigid suspension on either end can have effects on braking and handling. If a wheel should chance to bounce clear of the ground only gravity brings it back down, where a spring would push the wheel downward more quickly.