Tried with severe damaged iPhone 5, no screen, rear case looked like it had been in a war zone. Luckily the logic board is totally intact.
Bought new screen, new case and misc minor parts, there are several dozen different clips, stickers, meshes that you can buy as sets, but there will always be one or two missing. For example the small holder next to the ALS screw hole.
Anyway after full assembly, the phone booted fine, all performance parameters normal, including RF and actually passed Genius Bar warranty check and got a new battery.
Despite the successful result, I do not recommend it. It is basically impossible to get an undamaged and unlocked MLB, even harder if you want a pairing Touch ID, not to mention you CANNOT buy junk boards and hoping to scavenge parts and come up with a good board, all the major chips are encrypted as a set. The misc parts are difficult to collect and you definitely won't know the whole list without actually disassembling a few phones and be able to read Chinese shopping websites. These sites usually don't do international shopping and single order for a 5-cent part then $50 shipping is nonsense, especially when you need to order from several different sites and pay for shipping for individual orders. Unless you actually is Chinese and live in China, or want to spend $1000 and months of hassle just because you can, this is not for you.