That would be difficult, and expensive, to drill the holes after bending. It's also very long for a drill bit.
You may need a long drill, and drill before the ends are bent.
Or, drill at angles as a flat pattern, then bend.
Another option is make it a cast part.
No, do as Chris suggested, put holes and csks onto the flat part, then form....forming would require special tooling however.
The customer doesn't want this made from sheet metal. It's either machined, EDM or waterjet. from a block.
Sounds like it will need to be made from unobtainium...
It is possible to machine from a billet of aluminum (less the 5/16 holes). However, the cost greatly depends on the tolerance of the features/dimensions.
The holes can be pierced with a secondary tool (depending on the tolerance required).
A budgetary quote for such a tool, that would pierce one or two holes at a time, is around $14,000.00
We can send you a formal quote if you send us a detailed part print.
You really need to rethink your design.