No point in weld repairing a high stress area then grinding it all down to try to make it look unmodified. It will be weaker than stock and fail again shortly. I had this problem with a 70 Chevelle. It kept cracking even when stress relieved and annealed. The metal in the area was just fatigued and needed replaced. I got another frame an never had a problem again.
Your best bet is to find a clean frame for sale or a truck that needs work and swap frames out. As long as you have the title for the donor any check of the partial VIN numbers will be OK as you have proof of ownership of both trucks.
http://spokane.craigslist.org/pts/1637692804.html
I'm sure there are plenty more closer to home for you in the Portland area.
You are going to spend a lot of money transporting this truck to your dad. It would be a shame to have it black listed over $700 worth of parts.
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miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was
http://67-72chevytrucks.com/vboard/s...d.php?t=795577
69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been
69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc
68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E
79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars