Lawnkid,
First rule of thumb in this business is nothing takes an hour so you can leave that suggestion out of the mix. You have loading the equipment time, drive there time, dumping time and drive home time and unload all the equipment time. Usually that eats up an hour automatically, and it gets worse fast if you have anyone else in the truck with you cause the drive time multiplies.
Secondly, your going to have to get up and look in that bush to find out if your sheers will even go thru that hedge if your looking to cut two feet off. Your going to have to see the diameter of the stems at the 8 ft height to find out if your sheers will cut thru the material without hacking the bushes or constantly sticking up the sheers. If its two thick for gas sheers then that means all hand pruning and if thats the case Id recommend the lady cut them to seven feet so the thick stems are not in the new growth. Then be damn certain to sure she maintains them at the 8 foot height forever into the future.
A job like that unless your a real gambling man, Id suggest doing by the hour at a minimum of $ 40.00 per hour. Sure by the hour limits you to the dollars per hour you make, but that job that looks like 5 hours can turn into 10 or 12 in a hurry. You can find yourself working for nothing to do a real pain in the --- job, up and down that ladder.
Let us know what you end up doing.
CMerrick