Digitize Lps and cassettes to put on storage capacity on 256 gb IPOD.. Do Ihave enough space

Possibly, but it's not that simple to calculate. There are various factors to take into account that will affect how much space you need.

For example:

• an LP is not a fixed length. It may be as short as 22 minutes (I have one) or as long as 50 minutes. The longer the LP, the more storage space it requires
• Even a CD is not a fixed length. A CD single might be just a few minutes, a short LP could still be 22 minutes (the LP I mentioned above, released as a CD), or as long as 74 minutes for a modern CD, or anywhere in between
• pre-recorded cassette tapes will be the same as the LPs and CDs mentioned above. Home recorded tapes tend to be filled up to near capacity and it will be easier (but not easy) to calculate how much space they require.
• the Bit Rate that you use when creating the digital copy of the LP, tape or CD. The higher the Bit Rate, the better the quality but the more space it takes up. Music in digital form is now sold in a Bit Rate of 256kbps or perhaps even higher. Originally, it was sold as 128kbps, which is the absolute minimum that anyone should use for music. If any of the audio is poor quality speech, you might (note "might") be able to get away with a lower Bit Rate if your software is capable of using that (iTunes is not)

If you already have the iPod, that suggests that you are now committed to your planned path, which makes your question somewhat academic. So the only way to find out is to try it. I assume that you are already in the process of digitising all of this material, in which case, carry on.

As you add the media (music and/or speech) you can monitor how large the library is becoming. At the bottom of the iTunes window (if that's what you're using) is the Status Bar which tells you how many GB of storage the library is taking up. (View/Show Status Bar). Not sure how to do this in Finder (Mac).

If your library becomes larger than the space available on your iPod, one answer is to synchronise the library to the iPod by using Sync selected playlists, artists, albums and genres and then choose only as much as will fit on the device. You can even create Smart Playlists that can automatically remove and add media to the iPod at each sync and use this method to automatically limit what is added to it, while changing what is on it so that you don't have to. I won't go into details now, but I can if you think it might help.