Lakeeffect's 69 Valiant

As far as welding heads, no experience. However, cracked blocks on the 5.9 Cummins #53 blocks have been an issue. Some folks have used a "lock-n-stitch" system and have good results. See link: http://www.locknstitch.com/ there's some more good info on this site as well. I've had cast welded before, broken bolt hole tab on a std trans to bell. Ground both areas where the piece cracked, welder's clamp in place, heat area to receive weld until cherry red and stick weld. The head crack is questionable as to why did it crack? If you wish to chance it, drill a hole at each end of the crack to stabilize (stop the crack from spreading), v-groove the crack as much and deep as possible, heat until red and stick, mig or tig until full. I'd try to get another head though. . .