if performing a standard compliant test is important be sure to read and understand the actual standards document. There are typically formula for parameters the give ranges of permissible dimensions.
Did you do that, is 150 the minimum?
If you can not meet the standard, you can of course do the test and report the data with an asterisk, but it is important you should understand why the parameters limits are what they are. The reasoning is explained in the standards document. In some cases you are exceeding the accuracy bounds of the beam theory used for stress calculation (for example). In other cases you may risk generating a completely different mode of failure.
Sorry to be general about it, but I think Its to you to go study the standard and ask more specific questions if you need help.