With stock piston holes i use 20wt-35wt.If you drill the holes to 1.5mm then you'll need 40wt-50wt.
I race with 20wt oil with my hyper 7 and stock pistons in a bumpy track.
If it's smooth i would use 35wt front and 30wt rear.
BUT you won't know the difference if you don't try it out.
You will probably not notice any difference between 30 and 35 but you will if you go up or down by 10wt.