Are you wanting to stay with the 4.5x5 bolt pattern ? What is your driving like ? Mild , spirited or maniacal ?
I have 4 wheel discs on my 68 Barracuda and manual drums on my 69 340 Swinger . I realized I don’t drive like an idiot and the drums work fine . But I used a smaller bore master cylinder and larger bore wheel cylinders .
BTW…the Dart is a 408 W2 Solid roller 4sp.
Yes, my preference is to stay with the BBP, and my driving is between mild amd spirited and definitely not crazy. I haven’t ruled out going back to drums in all 4 corners - but is it possible to redrill Duster SBP 10” front drums/hubs to BBP?