Yes, the WB is the same thread size as the GM type.
I'm beginning to think there are a couple advantages thou to mounting them further downstream.
I cut up a sparl plug anti-fouler, and drilled it out to use for a bung, and then had it welded in right behind the converter flange (no actual converter). There are two sizes one 14, and one 18mm you want the 18mm.
Just angle it slightly so condensation doesn't accumulate in it.
When not in use I put a oil drain plug in it's place. I forget the part number but NAPA has them. Uses a 8mm, 5/16" allen.
Might as well order the Brue Roe Display board before he sells out. The two are a great match.