Big bucket of money if turning such into a semi auto firearm for you,and make sure that you talk to him to see if he can take the project on to begin with*.

First off, He has to convert the lower to semi with  AK FCG parts, then bolt to semi with block pin channel that needs to be welded in the upper receiver so the receiver will not accpet a full auto bolt, build/fit the the trunion to the barrel, then the fun of welding and fitting the upper receiver all together after he removes parts from the old torch cut receiver parts.

http://www.pirate4x4.com/forum/outdoor-sports-recreation/663044-pps-43-sbr-build.html

Bluntly, the only cheap way to build the rig quickly/semi cheaply is to just turn it back into a SMG. Here, the upper receiver is the only part torque cut, and so long as you get the barrel and trunion with the kit, then fitting such into the new receiver bent blank you listed and just the pinning and welding is need to complete the upper receiver back to a function SMG.

* To point out, your smith will need to be a FFL 7 to build the rifle out of parts for you as a semi auto firearm, since he is just starting with a bent receiver blank, and not an actual completed serial numbered receiver that he is just assembling instead (he will be producing a brand new firearm that needs to be registered with BATF since he is building the firearm as part of his business, and not just you building it yourself for personal use/ownership instead).

As for if he is building such into a SMG, then Gunsmith with a Class 2 SOT as a post ban SMG, then transferred to you on a form 3,  with  you a FLL class 3 SOT via a LEO letter of intent (to get the Form 3  approved for you to have a post sample SMG in your inventory).  As for him trying to build in under a form 1 only as a none SOT 2, don't think it will fly, since too many layers before it end up in your hands as a post sample to a SOT 3 under a LEO letter of intent.

To add, not sure why you are going with a PPS43, when a uzi parts kit is easy to build, and will handle/shoot a lot better than the PPS43 instead.

[url]http://www.robertrtg.com/store/pc/Parts-Kits-and-Build-Parts-c161.htm[/img]

Or if you want to save having to smith to build it (bending and welding the receiver together), then MCKAY ENTERPRISES UZI receiver, and you can pick up the needed parts from above  to assembly it your self