When I do mine, I bake them first at 550 for 20 minutes, then cool for half hour, then into the shot blaster. After that, we have a tilt/roller than gets out all the excess shot.

Compressed air in all threads. Chase out threads then brake kleen in thread holes first, then remainder of intake.

I tape off the carb base and intake runners and use a set of spare bolts and insert in all threads. Use an exacto knife or razor blade to trim excess tape.

I usually do one side at a time. If you spray the top first and have a set of 4 bolts installed at carb mount, flip over and let the intake rest on that, then shoot the bottom.