The plug and play replacement is easy enough to install, but keep in mind many modern switching power supplies aren't as rugged as the originals. I've had new Happ power supplies fail within the first year in a home use setting and with the proprietary header board add on from some vendors, finding an exact replacement with the terminals in the right order is a must.
Especially for Williams games, I like to stay with the original PS and the CMOS benefits from the power down profile of the caps on the original- something that new switchers sometimes corrupt.
Just my opinion, not meant to knock anyone's product. Whenever possible, rebuild the original, especially if all the numbers match in the game, it's just another small reason to be a good steward to the machine that will hopefully run for many years.