.050" Standard width probably, but that is not for performance width.
It will work fine, just not as good as a performance valve job could have, & I am not talking a couple CFM difference in a standard plain valve job compared to a performance valve job.
All these little items, seat width, proper angles, throat angles etc, can all add up to a whole bunch more CFM. Probably not too critical for what you are doing with this engine I think.
My prediction still stands, you have 2 days to get it running. Good luck!
