You can find the stock rom at sammobile.com
Also.. make sure you have an ICS bootloader... almost all the custom roms require that bootloader. You can find it at pershoot's site and flash it with Odin.
As far as good download's with md5's go.. this forum doesn't seem to use them as much as most forum's. So what I do is download a rom twice and check the md5's against each other.. that's not the best way, as you could have 2 bad download's, but it's something.. lol
If you can't find the stock 4.0.4 ICS rom at sammobile... I think I have it.. somewhere
I also have the ICS bootloader..
But if you're new to flashing and Odin... I highly recommend doing some reading and watch QBKings' video's..
I would also recommend(once you know that you have the ICS bootloader)that you use the infamous TWRP recovery.. it is the best recovery for this device ( I believe )..
E4GT : Project X Bare Bones
GT-P7510 : JB 4.3 CM 10.2/SGT7
Thanks Dev's for these Awesome Roms...