Hi
the reason there is side freeplay in the big end,(in a good motor), is because there are no thrust washers in the bottom end , that is why they have the thrust washers on the gudgeon pin , do not use any thing other than the factory thrust washers up there, remember, any thing made out of steel in a CZ mxer is made out of recycled Kalashnikovs and T18 tanks, including mud guards,fuel tanks and air boxes, strong but really heavy.
If you read a CZmxer parts book, page 14, you will see there are 4 size of big end bearings to match up with 5 fractional fit con rods .
Good Luck trying to save a buck.