There are plenty of Mini-ATX and Micro ITX Z87 motherboards which will allow you to overclock a 4670K without issue, and you can also get ITX power supplies if you can't find a small case you like which fits normal ATX ones. The only major bottleneck of a small case is the cooling and what GPU you can fit (there are small-form-factor GTX 750 Tis, but anything much more powerful usually only comes in full-size cards).
Additionally, I'm pretty sure Newegg will be better than Amazon as long as you're in the US.
Additionally, I'm pretty sure Newegg will be better than Amazon as long as you're in the US.
OS: Windows 10 64 bit Professional
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56
CPU: AMD Ryzen 5900X
RAM: 16GB
GPU: Radeon Vega 56