Back in the 70's, I was given a 70 Pinto with a 1.6 crossflow head that was wounded. After taking it apart, it had a burnt ex valve and cracked seat. After consulting with the wise shop owner that I worked for, I gound out the crack, we heated the head in the oven to 400F then brazed/filled the crack. Then, I had a seat put in it and ported the crap out of it. That motor got me though college and saw 7500rpm daily.