Hi,That would be poor form, since showing only two significant figures would cause a reader to assume that was the true precision. You would not risk implying a trailing zero, no matter what the text says.
I'm in the camp that the placement of the decimal is irrelevant except when there are trailing zeros. In that case it's better to use scientific notation to be clear.
And using constants at high precision is fine so long as the calculated results reflect the proper precision. The precision of pi is not in doubt.