Your shortblock cost will likely be about the same because it will all be aftermarket rods, crank, pistoms, etc. The top end is where the G3 will shine. Factory heads, lifters, and rockers. The intakes are still stupid expensive but your still cheaper with a G3 IMO.

When you get to ignition for the BB you need to buy, a coil, a distributor, an ignition box, and plug wires. For the Hemi you can use your stock coils and get an MSD Hemi 6 to handle everything else.

Your headers and mounts will likely cost about the same for either engine.