To answer your basic question:
Depends on the brake kit. There are brake kits from 280 to 380mm in
diameter.
I think the 16" has 286mm or so.

But usually, the biggest advantage of a brake conversions is not the
pure size, but changing from solid to vented discs.

Standard:
The first two brakings in a row might not make a difference.
But the third or fourth (downhill serpentines, the alps...) will have
heated the brake fluid over its boiling point, and air/steam bubbles in
the brake lines will make you step onto a squashy, useless pedal -> No
force transferred to the caliper.

Vented:
discs stay cooler, so stays the fluid, and keeps giving you a good braking.
Of course, sooner or later the brakes will boil as well, but it will
bring your safe through a lot more brakings than with solid discs.

looking at your post a second time:
A "brick" brake kit might work as well! It´d be like throwing an anchor.
:-)

Raimund

Am 13.04.2021 um 22:01 schrieb Dan N:
> btw... are the brakes on the 16" syncro the same size as the *"brig brake
> kits"* sold by our favorite vendors?
>
> thanks
>
> On Tue, Apr 13, 2021 at 11:13 AM Dan N <dn92610@gmail.com> wrote:
>
>> thanks Mark,
>>
>> so no need to upgrade to bigger brakes on Syncro 16"... :-)
>>
>> On Tue, Apr 13, 2021 at 11:11 AM vw_van_fan_Mark <madvws@cox.net> wrote:
>>
>>> Most if not all Syncro 16" models had larger discs in the front and
>>> larger drums in the rear.
>>>
>>> Mark
>>>
>>>
>>>
>>> Dan N wrote:
>>>> on the brake topic...
>>>>
>>>> Does anyone know if a Syncro 16 has bigger brakes than a regular
>>> Syncro/2WD
>>>> 14?
>>>>
>>>> thanks
>>>>
>>>> On Tue, Apr 13, 2021 at 10:33 AM Chris S <szpejankowski@gmail.com>
>>> wrote:
>>>>> I will be doing the same GoWesty upgrade within a couple of weeks on my
>>>>> Syncro Westy. I will report my experience as well.
>>>>>
>>>>> Chris.