Mike, I'm no expert, but my gut feeling is that it'll be OK, however if it was me I'd do a little bit of work deburring it and making sure there are no cracks or stress risers in it.
Next thing to consider is if the others would need shaping to match. I'm sure someone who actually knows what they're talking about will tell you if I'm talking rubbish or not!
You might find a local cylinder head place who can replace the guides though - I had my Superflow heads done many years ago.
Yeh I reckon they’d be fine may as well send them to be checked over by someone in the know you know 😉
Sent from my iPhone using Tapatalk