Here is the spark plug needed for Briggs and Stratton Intek and Vanguard engines as well as the spark plug cross references:

 

Intek — single and twin cylinder OHV
Vanguard — liquid cooled three cylinders, single cylinder OHV engines and 31 HP OHV V-twin.

Champion: RC12YC

NGK: BKR5ES

Megafire: SE-12RCY

Torch: K5RTC

The spark plug gap on these plugs should be set at .30.