Chevy P20 Step Van-King Project

[Psyekl]

I'm new to the forum (see my post in the "welcome" thread) and after only one day of poking about I managed to identify my step van with fair confidence: VIN # PS328F------

P - Forward Control (cab over)
S - In-Line 6 Cylinder Gasoline Engine
3 - 1-Ton
2 - Chassis/cowl/bus
8 - Model year 1968
F - Assembly plant: Flint (I assume Michigan, not Texas)

Darned handy forum! My step van has a V8 in it, obviously it isn't unrealistic to think that it had an engine swap. I was told it was a 350 though I haven't verified it yet (I am aware that the P20 came with 2 available V8s in 1968).

I'm planning a rat-rod RV project and I plan to tow a small trailer. I need to upgrade the suspension and brakes, steering, engine and transmission. I have experience in a metal fabrication shop and have assisted in building a couple of race cars among several other interesting projects. I'm lucky enough to have a friend who is a fabricator, access to a metal shop as well my own wood shop and garage.

What I do need help with is the knowledge of people with more expertise with old Chevys and Chevy step vans than I have: I do not have a lot of experience with older vehicles and I certainly do not have any experience with industrial cargo vehicles. My searches have not turned up much to tell me what I need to know about where I can find parts for upgrading or what vehicles have parts that are interchangeable to use for upgrades. I can always pull entire suspension systems off of something modern in a junkyard and fabricate it on, but I'm not looking to do that much work and would rather just try to stay as simple as possible.