No. There's no way you'd be riding an hour at FTP 2 days after a 350tss road race. As I said, I did 1h at 300w, which wasn't particularity difficult, but not a cake walk either. My ftp is around 350.
So to do 340, you'd be looking around 370 real ftp.
Not many people would go out and knock out an hour at 340w. Would put threshold around 370ish.
He’s got an engine indeed.