Sorry I didn't see post #9. This is that happens when OP does so far into a thread. Plus forgive me as I having a nightmare of a week with a distributor and not all posts shows up here at times. I about to hit them to the curve. They change their software and expect me to pay for their mistakes. I got two packages coming out the same warehouse so they either double shipped the order or they put each OEM in a separate box. I won't know until FedEx shows up late Friday.
So I am now confused as the serial coming back one model, you find a model number in an unusual place than where I usually find them. I beginning to wonder how screwed up is Briggs lately. IL mention if the serial is entered differently it might come up with a different model but I several ways and only one worked on the Power Portal which was 1204105472598.
As for the PN you just going to have to order it to see for yourself. But here is a measurement layout from Amazon provider which I would trust more than a random size not against measure layout.
View attachment 68166
Appears to be 6 x 4-5/8