It is true that most of the world's urban areas are becoming larger, with megacities like Delhi, Jakarta, Shanghai, Beijing and Manila adding more than five million people in the last decade and most other urban areas are growing, but not as fast.
1 With professional installation, a central vacuum system can cost $800-$4,000, but averages about $1,200-$2,000 for new home construction (or as part of a remodeling project where the walls are already torn open) and $1,500-$2,500 for retrofitting an existing house.
I would recommend a 383 with afr 195cc heads and a matching hyd roller cam. You would probably be looking at ~500 hp for close to what you would spend on the motor you are looking at. This is essentially a long block of the 425 hp GM 383 for $5000. Here is an AFR headed 383 to consider for $4150.