cinder blocks are for walls. they are only average for that use. please dont use them for support of any kind of vehicle.
you can rent jack stands from a local rental shop. at least you can in chino valley az. thats the nearest one to me.
there is no substitute for good safety practices. ive seen all kind of accidents happen because the injured party did something dumb. i have one less knuckle on my right hand doing just that. a table saw does not play favorites.
it takes only a second of bad thinking to give you a lifetime of pain, or worse
kill you.
is your life only worth a few dollars??? how about your wife and family. overboard thinking? maybe, but these types of things kill people all the time.