67-72 lwb was 127" and 73+ lwb was 131.5 - so, probably not a very fun project
. Also, even if converted to part time, the NP203 is chain-driven, not quite as strong as the 205, another consideration on the running gear. If you have a C10 you want to swap onto it - you could swap the axles onto the C10 chassis - a bit of work for the front, but some folks have done it. Probably not worth buying a whole truck for its axles and so-so t-case though.