Probably best to deal with one issue at a time...

First, need to know if the engine is apart, or are you leaving the stock bottom end together??? Either way, need to know how far down the cylinder the top of the piston is from the top of the block. If the block is apart, then it should be zero decked to have the piston at the top of the cylinder--this along with other factors determine the "squish" height, which in turn is used in the formula for the true compression ratio.

Second, a stock 700R4 IMO is not going to stand up behind 400 ft. lbs. of torque---as Pat mentioned, this is a pickup, concentrate on building the engine for torque, not horsepower. It takes torque to get that mass moving, and torque is also what fries automatic trannies....

Third, takes a lot more then just wide tires to make a pickup hook. A tired that wide is just creating a lot of rolling resistance that the truck doesn't need... A 275 or 295 radial tire on a 10" wheel gives a plenty big enough tire patch to make the truck hook, but no tire is going to hook with stock, worn out rear suspension.....

Everything has to work together, as your father in law said, but it takes more then a good engine to make your truck (or any vehicle) fast....