I had an 80 B300 with the heavy duty front suspension. It also had the 16.5 wheels. I ran the 9:00 16.5 tires on my van, and those would rub on about everything when you turned the wheels sharp. My tires rubbed against the frame behind the tires, and the front inner structure at the inside of the front end. They were also very close to the front bumper corners, and on bumps would make contact with the outer sheet metal in the rear fender dog legs. Taller tires will likely reduce the amount you will be able to turn the front tires.

I don't know how the height of what you want to run equates to the 900 16.5 tires, but anything taller or wider is not going to clear the outer or inner fenders and frame, and a taller tire probably isn't going to clear the floor pan, when you turn the wheels to the right or the left.

If you need the amount of lift you are talking to fit the tires under the front end, it probably won't turn very much once you get them under it. You will take a huge hit on the already long turn radius the B vans have to begin with.

I did run dirt track cars before. You can probably hack out anything that interfered with the tire movement to get the clearance you desire, then build back in the structure you need to make the van functionable again.. At some point, any tire will fit anywhere. How bad do you want those tires?

Dodge made the B vans in a 4x4 configuration during the time period of your van. The 4x4 versions were much higher off the ground then the rear drive vans were, maybe that could be a direction you want to look. You only need to mount the front axle and connect the steering, the rest of the 4x4 stuff wouldn't be required. Gene