PS3 pup are never bigger than 256mb. It sounds like you found a set of PS4 pups. Links are here, along with a hash so you can check your download
http://www.psdevwiki.com/ps3/4.82_CEX
That is the old version, I don't know how you got there
On the
http://ps3xploit.com/ page click the link at the bottom to the forum, then click the CFW forum, there are two sticky posts at the top.
Both of them have the files in the first post.
That is if you want to dump your nand/nor and verify it before you start. It's mostly in case something goes wrong and you need to restore, although you will probably have to use a hardware flasher to restore. I can't remember if I did this or not, I probably dove straight in.
On one of the sticky posts it's right there at the top, on the other click the Flash Writer tab, click "spoiler" & then click the usb tab.
"WARNING: USE ONLY THE PROVIDED flash_482.hex AS IS. DON'T PATCH IT OR MODIFY IT OR YOU WILL BRICK *****
- Verify flash_482.hex file on a flash drive and in the selected USB slot!
- flash_482.hex MD5: d05be52f8d21700052fbd1fc0174acae"
First you need to find out what flash type you have, nor/nand. Slims are all nor, fats are a mix of nand/nor, super slims are emmc (but they aren't compatible with CFW).
http://www.psdevwiki.com/ps3/SKU_Models#Retail_Models
If you want a backup then on the "Flash Dumper" menu use "Dump IDPS" and then "Dump Flash to USB", then the option for your flash type.
To flash the hex (which allows CFW to be installed) you need to use "Flash writer", "Write Flash From USB", then the option for your flash type.