project questions??

[SkyBlue72']

I'm thinking of building up a 71 or 72 lwb c10 from ground up. what's bothering me is I see you guys buying cabs and frames, etc., and I was wondering if you have to deal with vin numbers on each seperate part.
You see I had a friend of mines who bought a custom 69 stepside, and was later hassled by the cops who gathered up all the numbers on the truck, like the frame, cab, etc.. As they ran them they found that none of them matched up and that it was considered stolen and it was soon hauled off. And boy, was that thing nice, it was paint some tang color w/ a mid 90s fiberglass stepside bed on it, with a four link rearend and custom frontend also.
My questions is what do you guys do to avoid this delimma or do you just build it without a worry?