Fixed/tracklocross wheelset 135mm/120mm conversion

Hey there, building up a so ez which has 135mm rear spacing, looking for one of the following:

• single speed disc wheel (to run with bolted cog)
  
• 135mm fixed wheel(set)
  
• 120mm fixed which has conversion kit/is convertable (i.e. some halo hubs)
  
  

Thank you!