Besides the shorter nose on the 5-lug Type I drum, the friction surface is also narrower (as were pre`68 shoes) - so narrow that `68-up shoes may not even fit fully inside the drum unless you cheat and turn the drum a little deeper. Plenty of folks have managed to Mickey-mouse 5-lug rear drums onto `68-up brake assemblies by shimming them out, but it's hardly what I'd consider a professional solution. You can use `65-`67 brake assemblies (backing plates, wheel cylinders, shoes) if downgrading to the narrower linings doesn't trouble you - but you still need a spacer between the drum and the axle nut (it's a good idea to check the axle nut torque at least a couple times a year if you run a spacer).
Bob Ingman wrote:...Have you looked into using 66 T-3 drums...
`64-`65 Type III 5-lug rear drums are the same diameter as the `66-up 4-lug (251.5mm) so they would require that the larger (and heavier) Type III backing plate assemblies also be used. Not a bad move as far as stopping power goes, but not much help if keeping unsprung weight down is important.
EARLY Type III (`61-62 to VIN 0076299) used 231 mm drums and 40mm wide shoes; `63 (to VIN 0221974) had 45mm shoes. They're both 1mm larger in diameter than Bug drums, so it's not likely that you'll find a used one that'll still have a successful radius match with a standard Beetle shoe - but having the shoes relined with "oversized" (1mm thicker) lining material will solve that problem.
The swingaxle Thing drums are nothing but ½-ton Bus items (pre`63, through VIN 1144302) and they ARE 230mm x 40mm. Of course, it's not likely you'll find one of those that hasn't been turned too big to fit properly with standard Beetle linings either - but the oversized lining trick still works, and you needn't be overly concerned about them being too thin for safety on the lighter vehicle (out to about 9.15", at least). They were popular with the off-road crowd about 40 years ago...I can't recall if they needed any machining at the lip to fit `58-up Type I backing plates but that'd be easy enough to do if you have a lathe.