I have been contemplating putting one of these engines in a classic chevy truck 60-87 and was curious to the total dollar amount it might take. I plan going the step van route as a donor and keeping it stock and using the 400 transmission.
You have a lot of variables that can significantly affect the cost of your overall investment which include but aren't completely limited to:
The initial cost of the P30 van.
The condition of the 4BT engine that is in the van. Any repair work needed?
The decision on if you want to scrap the van body or do a double engine transplant which can recoup anywhere from 75% to 125% of the van's initial price. This of course would be based on the P30's mechanical condition and appearance.
I have looked on dove bid and they have trucks going for $1500 to $2000 with good engines. To recoup most of my losses I had not considered doing a double swap and put the gas engine in the step van and may sell. Mechanically I think I could handle it but I think the biggest pain would be the engine mounts which I take would not work from the step van. I could probably find someone to help though. I really like the idea of a classic truck that gets better mpg than a 4 cyl s10 and that I can easily work on with all that space under the hood.