Yep, but think of the cross section you'd be blocking when doing that. You'd be seriously inhibiting flow.
If you can weld aluminum, it's probably better to just weld some bungs on at ~35*.
Also, I indicated the wrong plane to be working from - you can have them at 35* to the vertical plane (the intake mounting surface), pointing at the engine. Steeper angles are better, though, to lessen the arc that the fuel takes between the injector nozzle and intake valve.
To really get the setup done nicely, you could put the injectors in at nearly 90* to the intake surface by drilling/tapping the lines into the curve in the intake pipes, just after the plenum.
PS - you can use a brake line with air tool mufflers on them instead of making actual injectors for the setup. It's called a "bleed feed", where the same vacuum that turns on the fuel sucks it from the lines as well.
You have to drill the manifold out a little larger, and put a fitting in it that you can fit the air tool muffler in and still be able to thread the fitting into the manifold, then screw the (custom bent) brake line/fuel line fitting into the bushing that you made.
