It may come threaded but you'll need those threads chasing before you install a bottom bracket and to do that you'll need someone with the T47 tool. They are very very rare.
WTF? Shouldn't the builder of any custom frame be chasing the threads after welding/before delivery, particularly if they are supplying direct to the customer rather than a shop.
WTF? Shouldn't the builder of any custom frame be chasing the threads after welding/before delivery, particularly if they are supplying direct to the customer rather than a shop.