Alright, I have updates! Suffice it to say that Chadrinkincat's instincts were good.
Here's the reply regarding the less expensive pot:
Thanks for your enquiry.
Yes, this is a F1 Teapot from green label period. The capacity is around 80~ 85ml.
It is actually a Zini Teapot with Hongni coating both on the inside and outside of the pot.
Seemingly it is at least F1. How good a pot is this or the 內紫外紅 style for tea drinking? My current vibe is that most of you would say it's best just to buy the $400 pot or stick to a gaiwan for now, following the buy less but buy better philosophy, but I figured I'd check
(Slightly revised this for clarity)
Here's the reply regarding the second pot:
As for Teapot ZA0103, it is a pure Hong ni teapot from mid 70s
I asked whether this was the pre-77 Hongni or post-77. I think this means pre-77 switch, though I guess 77 might be considered part of the mid-70's and the switch presumably happened at some point during that year.