A Few Questions About Stamps Of Iran/Persia

I've dabbled in Iranian stamps off and on for years (I've always loved the designs), but it's been a while. I'm fully aware of all of the issues regarding fakes and reprints in the early material. I have the Persifilia catalogs to help differentiate.

My questions today are more about the modern material, say 1940 and later. I had an opportunity to purchase a collection of MNH material going as far back as 1939 at a decent price, and did so.

In addition to Scott and Persfilia catalogs, I also just received the 2017 edition of the Farahbakhsh catalog, as it covers later material a bit more in depth and also offers FDC pricing.

Question 1: When I convert Iranian Rials to U.S. dollars, the prices in the Farahbakhsh catalog end up being WAAAAAAAAAY lower than prices for the same items in Scott and Persfilia. The difference is radical enough (like nothing after about 1940 is worth more than about a dollar or two, including sets that list in Scott for $50+) that I can't help but think there's a conversion issue. Has there been a major currency revaluation in Iran since this catalog was written (2017 edition presumably published in 2016)? I have an email in to the company, but have not yet received a response.

Question 2: How would you value/price post 1939 Iran material that is MNH but Scott does not differentiate (material prior to the point where all Scott listings are MNH)? Farahbakhsh offers a +% for MNH different for each issue. Persifilia offers discrete MNH pricing but stops prior to this material (at least the 2 volumes I have). Perhaps apply the Farahbakhsh percentage to the Scott value?

Thanks in advance.