What type of ign system on eng-points/magneto or points/12v coil?-the K321 came both ways.
Regardless if a mag or 12v ign system,as has been said confirm that points are opening/closeing,if not,either points set incorrectly or plunger/push pin for points may be stuck in block due to rust,after confirming points operating,clean point contacts as same may oxidzed,disconnect coil/condenser lead(s) from points,connect an ohmmeter/battery powered test light between terminal on points & eng block.
With spark plug out,rotate flywheel slowly by hand,confirm you get a zero ohm reading/light when points close,if you do reconnect coil/condenser,if this is a mag ign leave kill lead to ign sw disconnected from points/coil,crank eng & check for spark.
If you have spark now then problem in wiring harness,ign sw/stop sw or safety sw's on tractor/equipment that this eng is mounted on.If no spark with kill lead disconnected,then problem on eng-points set incorrectly,bad condenser,wire from points to coil shorted to block//point cover,poor coil ground connection due to rust/dirt,bad plug lead or plug.
If ign system points/12v coil,check that wire from ign sw to coil is connected to +(pos)terminal on coil,if polarity on coil reversed you won't get spark,turn ign sw to run position & check for 12v at + terminal of coil,if you have check points as above,if points working ok disconnect lead from ign sw to coil,connect a temp lead to coil & battery +(pos)terminal,crank eng,if you have spark now,then problem in wiring,ign sw,safety sw's on tractor/equipment,if still no spark with direct connection to battery,then problem on eng.