Just hold out for one with a 7.4.
No reason to do it the hard way ....
Maybe I'm spoiled, but my '92 has plenty of get up and go.
Don't have any issues merging onto the highway, or passing, or whatever.
Seems to have a sweet spot at around 70mph.
It acts like that's its favorite speed.
Is the van you drove running correctly?
Is it a conversion van?
The way you described it, it sounds like a 6 cylinder, high roof, conversion van.