Another advantage here also is that these forks raise the front of the bike up an inch or so- since a cruiser often is long in the engine mounting section, the motors are hard to get level- having a shock fork helps a bit. You can more likely use a straight billet intake- a guaranteed performance enhancer for only about $20, if the motor is level.
If you're getting 30 or above, I highly recommend- your'e less likely to get surprised by a jolt on a pothole or bump and lose control- also the larger 700C wheels are a plus in this department.
here's another listed:
A replacement, or a first suspension fork for a mountain bike frame will probably take a fork with a 1 1/8" steer tube- there are some listed there too: