I've had no problems with Scat 10172 8740 studs at above those HP levels, Richie stocks them. Very nice quality.
Cheers
Phil
I haven't used the CB or CSP ones so cant comment but I did have some problems with Bugpack ones a couple of years ago stretching when I torqued them up, only odd one or two but wasn't good
as Phil wrote the Scat 190,000 psi version are really good but if it was me for your engine I would get some genuine old stock german ones from an old case and use them
cheers Richie