The problem with any mechanical work being done while on the road is finding a shop that has the proper equipment. If you are at a small ill equipped shop with minimal equipment and staff, you are going to sit there longer.
If the block has to be removed, the shop with the proper equipment could drop it out the bottom while a shop that can't do that has to deal with taking it out the top, and maybe through the windshield, which will probably take longer.
This is a tough call and there really is not way to predict what it will take to complete the job, especially if you do not know what has to be done.