Learn to use one or both of these calculators now. It is better late than never.
You have only several more days until you have to put your robot in the bag. It is quite likely that a thoroughly tested version of your final gearbox design will not go into the bag. If you bag your current gearbox design, it is likely to fail and you will be relegated to playing defense. Not much fun as my team discovered last year 
Have you built a practice robot or do you intend to do so? If you are, you can test your gearbox solutions on it. If not, can you replicate just some parts of your elevator design so you can test your gearbox solutions?
It is just over a month until your one Regional. If you plan your work well and design the gearbox mounting so it is easy to install, you can go to your Regional and install a proven, robust gearbox design in a short time and still have time for some practice matches and have some fun. You may also want to keep your elevator carriage and intake mechanisms and refine them further along with the gearbox. Quite a few teams do this to effectively extend their build time. We are.
You have one shot at this so learn to use the calculators that AriMB linked and make it a good shot. Best of luck!