Solder as many connections as you can. In addition to soldering the green wire at the MAP sensor, I like to solder the wires under the dash to the crimp connectors that go on the power block, just one less thing to worry about at high boost.
If you don't have a soldering Iron, it would be the perfect time to get one, the portable butane powered ones are pretty inexpensive at HomeDepot/Lowes.
There's a rubber grommet (HVAC Control) on the firewall near the ECM, and you can drill a large enough hole in it to run the wires from the pump, MAP, & float into the car. Just use a coat hanger or some very stiff wire to pull the wires from the engine bay down into the car, there is plenty of wire to then route to the drivers side.