Man, a '46 has drum brakes all the way around, a single cylinder master cylinder, and not a whole lot in the way of suspension.
Simply put, there isn't much (if anything) on a stock '46 frame that you'd want to go much faster than 45-50MPH with.. so about the only thing you'll be using from the original rolling chassis is the frame rails, anyway.
If it was me, i'd look for a later model (perhaps 70's) Chevrolet truck or Suburban that already has the engine, tranny, rear, suspension, brakes, power steering, air conditioning, etc and put your body parts on that.
You'll get done a whole lot quicker, get it done a whole lot cheaper, you'll end up with something a whole lot safer, and if you ever need to do repairs in the future, it's a whole lot easier to ask the Auto Zone guy for a radiator hose or drive shaft for a '76 Burb than it is trying to remember what the heck part you used when you shoehorned all that stuff onto a 60 year old frame.
Finally, if you ever decide to sell it, the resale value of a truck thats had a full frame swap is usually higher than one thats been cobbled together from various other vehicles.
