The current, available ASTM D1003 Haze Standards have nominal Haze% values of 1, 5, 10, 20 and 30 with air (transparent solids) or the transmission cell filled with DI water being 0 (transparent liquids). Here are some thoughts on further options.
Thirty (30) is not a magic number but above that value, it is considered that your samples are moving from a transparent material to a translucent material.
As a metric, ASTM D1003 Transmission Haze was designed to measure scattering in near clear, transparent materials. At a level above 30, you are moving out of the intended range of the metric.
If you have an instrument that is measuring an ASTM D1003 Haze 30 standard in close agreement with assigned values, you can have a high degree of confidence that it is reading haze well above that point. However, please note that when you get above 50, you are well beyond the intended use of the metric.
At this point, we generally recommend that customers use Y Transmission (C/2, D65/10; Total Transmission mode) to separate lot differences in translucent materials. Y Transmission measures the total amount of light that comes through the translucent material with air (transparent solids) or the transmission cell filled with DI water being 100 (transparent liquids).
If you said that you need a PQ performance Qualification standard at a Haze level > 30 to verify instrument performance, you could make your own by purchasing a chemically abraded glass sample (at least 50 mm x 50 mm in size) and benchmarking the Haze value yourself.
Glass is very stable and if kept clean should serve this purpose well.
This abraded glass sample could be measured on your instrument over time in comparison to your baseline values to verify that the instrument is consistent at this higher level of haze.