And another thing
You SAY that weight is not an issue.......and you are adding a small block.
Just wondered if you have ever driven this van?
Not trying to be a samrt ***........but these creatures had a straight axle, and leaf springs as I recal..........the motor was nearly IN FRONT of the axle, and the weight distribution was VERY weird.
To say the least the handling in them was Squirrely as HELL!!!!!!!!! They would swap ends in a heartbeat!!!!!!
Adding the larger motor made it worse.
I knew several guys that went the mid engine mount route. It put the weight of the engine right in the middle.....ran a very short drive shaft......and most of the ones I know could pull the front wheels if you could get the wheels to hook up.....it was FUN!!!!!!!!
I knew one guy who built a clear dog house to cover the engine so you could see it!
Other just made a new dog house, and put a table on the top with some nice holders for your beer.
A word of caution.....you'll probably need to beef up the springs and shocks, and make sure the front brakes work really well because the rear ones will be worthless when the weight shifts!!!!!
The other thing is...........pulling the wheels off the ground will almost always spill your beer.