CB550F2 1977 rear wheel bearing size

[TonUp]

I have just had the rear wheel drum lining trued up on a lathe and now need some new wheel bearings.
Just ordered a pair of bearings for "rear wheel CB550 '77" off ebay and I got two 6304-2RS. Now I realize that the right hand is a 6304 and the left hand is a larger 6305 size. 

I am not an engineer, so I am not familiar with the bearing numbers.
Searched on ebay again for 6305 bearing and found this one;
6305 25x62x17mm 2RS Rubber Sealed SKF
http://www.ebay.co.uk/itm/6305-25x62x17mm-2RS-Rubber-Sealed-SKF-Radial-Deep-Groove-Ball-Bearing-/191514305444?hash=item2c972463a4:g:XN4AAOSwNSxU7KSX

Is this the correct bearing for a CB550F2 1977 left hand side? TIA
The 6304 bearing that I got is made by 'challenge' - should I junk it and get SKF bearing (as recommended by a mate in the pub last night).

[Bryanj]

If its the same number its the right bearing and all bearings have to be to a minimum standard so i would use the one you got,SKF probably manufacture to a higher standard than minimum

[TonUp]

thanks, sorted