Apart from normal rebuilding processes, pumping a 350 to 383 will require the lower end of each cylinder to be clearance ground away to provide clearance for the connecting rods and nuts / bolts.
Check out the following link for a better idea....
https://blog.k1technologies.com/how-...ker-crankshaft
Depending on the actual engine out of the "truck" there may be other areas that require close attention....
If this was my sons first engine build, I would be recommending a later model single piece rear main oil seal, factory hydraulic roller cam 350 with some aftermarket heads....
