It would need a 16 inch barrel. Which defeats the purpose because it looks stupid. Only way to mitigate the stupid look, is to add a barrel shroud (faux suppressor). Because you're spending at least $2500, it's a waste of money because you can't use it to it's true potential (SBR).
Only reason why I would buy it is if 1) I had buku dollars and 2) Convert it to the SP5SD (MP5SD) version that has the faux built in suppressor. Need to meet both requirements or not buying.
If you do have the money, since HK is making them again, the quality will be very good. Prior to, HK stopped making them and you would have to get clones like POF (Pakistan Ordinance Factory) which is made in a mud hut in Pakistan or other poor quality brands. It was pretty much a 50/50 with a lemon or good SP5. There was 1 guy in the US who did make them, but price was like $3800 and IIRC, he retired. But even he got the parts from overseas and assembled it here.
Some companies did make the 22 LR version, Walther, GSG, Atlantic Firearms.