Try to read the non-punctuated parts as mushed together as you can then as clearly as you can. Find the differences between those two renditions and you'll find where most of the other caesurae need to go.
There is not a caesura in "footsteps scrape" because the two sssss's slide together - there is no stoppage of breath or major rearrangement of mouthparts. "scrape the" is a pretty obvious one, your mouth has to close completely on the p and reform to make the th. It's hard to say pth without putting in a transition of some sort(p||th or puh-th).
On "buffet well", I'm wondering if Pope pronounced the T there - if he did it's an obvious break. "buffay well" I'm not so sure about.
"doctor and" in the last line is a more subtle one. In the clearly spoken version, I make a sort of soft glottal stop there.
