The big thing is how much other than the engine compartment is affected. If it is just under the hood, it really isn't all that bad to fix, just replace stuff.
If it melted things inside the firewall, under the dash, it gets way more difficult and expensive. The problems can be just from the heat of the fire, or because wires shorted and melted other wires in the cab before the burned off. Shorts can take out all the computers and other sensitive stuff.
You are correct to look for some experienced help and perhaps a donor van, as at this point you really don't know how bad it is.
I have a 1997 RT with the Dodge piwer plant.
Do you know what caused the fire? Want to keep an eye on that in mine too.
By the way....I too painted mine all white.
With a little red and blue striping.
Kinda a stealthy look.
Wow, so sorry to see that, I really hope you can save it, the rest of the van looks in great shape. I have a 1997 , so I also am interested to hear what you think was the cause,, keep us updated if you can,,, take care,,,,