I have a 12v 6a Power supply that can plug into the MEGA 2560 board, can that power the RAMPS 1.3 ? Also If I have a regular 350 Antec Basiq power supply can I just cut the right combination of wires and plug those wires into the screw terminals on the top board and power the RAMPS without having to make a LAB Power Supply?

You do not plug directly into the MEGA 2560 as far as I know. You night have to if you use the SD card option.
The smaller power suppply should be ok if you do not have a heated bed. Then the power supply will limit the amount of power available.

Yeah Thanks got it all working