It is fine, any B250 chipset will support 64 bit.
http://www.biostar.com.tw/app/en/mb/introduction.php?S_ID=865#specification
OS SUPPORT Support Windows 10(x64) for Intel 7th Generation Processor
※Support Windows 7 / 8.1(x64) / 10(x64) for Intel 6th Generation Processor
what CPU do you have in mind?
Why not get coffee lake or Ryzen 2? Any components you already own? Newer platform may be also cheap but has better performance.