Drilling rear drums

So I am in the process of swapping out the center section on my 8.75 rear axle from a 741 case 3.23 open to a 489 case 3.73 sure grip unit. I also acquired a set of a-body BBP axles that I would like to put in so I can get rid of the SBP to BBP spacers/adapters that are currently on my street driven Duster. I would like to swap out backing plates and all associated brake components from 1 3/4" to 2 1/2" brakes BUT it's just not in the budget at this time. Can I just drill out my current 10" SBP drums to BBP and be on my way? I know it's not ideal but it should work for the time being. Or am I missing something?