[ECI-EN] ISO 12647-2 Paper Type 4: which?

Hello, I am involved in bringing a sheetfed press to ISO 12647-2:2004 printing standards for paper type 1, 2 and 4. Therefore, I measured all common printing stock that this particular customer uses with a Gretag Spectrolino, and ranked them according to the conformity of the Lab values for these particular paper types. It was no problem finding paper fit for types 1 and 2, but every sample I took of his uncoated white stock was too blue. The b* values were going from -6.4 to -7.2 (white backing). My advice to him was to get some Zanders Zeta Matt white, because that was used for the Altona tests. Is there any other paper that qualifies? Best wishes, Yann Bouckaert Sagam Belgium