So, you are asking what accessories from walther/Umrax made mp5 22lr May be transferable to your sp5?
I don’t know. I would say nothing internal will work. I serious doubt the stock will work either. Maybe the drum sight will fit? I don’t think you have a top pictinny rail on the mp5 22lr. Otherwise, you prob has tested it.
Imho, you may as well buy the accessories and parts for other mp5 clone makers and have better chance to work. No need to go that cheap.