Spark Plug

I have a quick question regarding spark plugs and the different designations. This may belong in the mini forum since the meat of the question is for a KX80 but I figured it was more maintenance so I posted here.
Buykawasaki.com lists the stock plug for my sons 99 KX80 as a NGKR6254-105, when I asked for this plug at the local dealer I got a blank stare and no plug. The bike when I bought it used has a BR9EYA in it and runs fine. I currently use and have a box of BR9EGV's for my RM125 and someone else has suggested I should run a BR9EVX so at this point I am completely lost. What are the different designations on the plug and will I be safe as well as will the bike perform up to snuff with the BR9EGV's that I have or what plug should I run since none of the bike shops have the stock plug and the only Kawi dealer is closed on Saturdays :(

Thanks, I found this AFTER I pulled the rookie mistake and didn't do a search. I was in a rush and looking for a quick reply. By my interpretation BR9EGV and BR9EVX would be interchangeable just a slightly different electrode. As for the stock plug hopefully the Kawi dealer is at the race tomorrow and I can ask them.