Best way to find out what wt the blank is will be one of two ways. The popular way a lot of builders do it now is with the CCS (common cents system). Its a system that came about not that long ago to determine line wts. It looks pretty intemidating at first read if you have never seen it, but click on Step1 and read the pdf file and it explains it pretty well. Not that hard to do.
http://www.common-cents.info/
The only thing I don't like about the CCS is that it is a static test, and actual casting of a fly rod is kenitic energy so IMO I don't think the CCS system is "dead on" like some guys feel it is. But it for sure is a good system that will help you find what wt your unmarked blanks are.
The other way is to simply tape the guides in position and go outside with a few different wt lines and test cast it with 30' of line out from the tip and see how she feels to you.
Steve
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