As long as it isn't MyAnusFire, knock yourself out! :evil:
No idea about your cells but I tested some for a buddy and of the 4 I tested they were all between 675 and 1000 mah. Lesson learned for you and him - well hopefully learned 
Do you already own a battery charger? If not then consider the Opus BT-C3100 v2.1 since it can not only charge your batteries but measure the current available, discharge your batteries and measure the internal resistance too.
Here is a review of it Opus BT-C3100 v2.1
I forget which endor sells it for the best price but it seems it is in the $36.95-39.95 range.
It's not the capacities of the UltraFire batteries that you need to question....but do you want to risk a catastrophic failure to life and limb (not to mention home FIRE) by using them and saving a few bucks. I think NOT.
a data point.
i got a deal on amazon for 6 securityling 3 led version last week.
seller stated they were last of the old sku.
so is the new sku cheapened?
these are the good ones with the threaded shelf.
we of course could hope the new sku is improved but as srk’s go i doubt that.
here is a good review of the skyray king:
I don’t think there’s such a thing as “THE” SkyRayKing.
They’re all clones and clones of clones…
(edit) …and welcome to BLF 
Do yourself a self righteous and Read HERE
There is info to sign up for nice batteries too.
If you want an SRK, READ my friend ;)
Actually, there used to be authentic SkyRay Kings (3 emitters). Things got nasty when the clones started to appear…
Of course, it started with the genuine SkyRayKing, but that was years ago.