It’s not irrelevant since going from 60% to 90% doesn’t take 2 years+.
Importantly, starting from the 60% enriched material, a single cascade of 175 IR-6 centrifuges could produce the “weapons-grade” material needed for one nuclear weapon every 25 days.
You were talking about 9,000 kg of 3.5% enriched uranium. You said the 60% HEU was a smokescreen and Iran had 9 tons of lower grade enriched uranium.
Keep in mind in your calculations there is about 200KG of 20% uranium inside the stockpile as well, which is what I referred to as the quickest route to a bomb if the HEU stockpile is taken.
I can redo the calculations for this 200 kilograms of 20% uranium if you want.
I'm going to spare you the details, but the bottom line is this:
You will get about 44 kilograms of 90% HEU in 2 months, assuming you have two cascades of IR-9. Each cascade contains 164 machines in a typical configuration like IR-1, IR-2 and IR-6 and assuming IR-9 has a SWU of 30 per year.
That's enough for nearly 6 fission devices, assuming a relatively typical compression factor of 2.
Again, the issue of converting this 44 kilograms of UF6 gas into uranium metal is still there.
Also, our devices won't be boosted-fission bombs because they have already destroyed our deuterium and tritium facilities. Hence, lower yield.
There is also the plutonium thru the spent fuel rods of the nuclear plant part that can be done in days, but I picked the most covert route first.
Plutonium that we can't get our hands on it because the Russians are there, and we do not have facilities for plutonium reprocessing to the best of our knowledge.
Also, the plutonium that we get from the Bushehr reactor in its current civilian configuration has a lot Pu-240. We need to reconfigure the Bushehr reactor which is not possible while the Russians are there.