How to export full size image from Lightroom?

I'm working with a print company to blow up 3 images to 10ft l x 8ft w. My print company told me this for "full size" images.

"IF you are looking to do a banner that is 120" x 96"
Make your photo 120" x 96" @ 75 dpi

9000x7200 @ 75 dpi in theory"

My trouble now is exporting from Lightroom and keeping the image full size. I shoot w/ a Nikon d5500 in RAW and edit slightly, so after I click export, what settings should I export at so it's big enough for the print company to make the banner? I'm thinking TIFF… And should I save it on desktop, send it in an e-mail or put on the SD card?

In LR:
1. Crop your image using a custom aspect ratio (Enter custom) of 9000x7200 (LR will do the math and make it a 1.25:1.00 aspect ratio). Use the crop handles to put the crop frame where you want it. You will end up with the width being chopped due to the aspect ratio you want.

2. In Library mode,
Export your image with the following settings:

File Settings: whatever you want. A high quality jpeg setting (90, or so) will work for photographs, TIFF is useful for graphic images with large areas of the same color. If you use TIFF, use compression (ZIP). A non-graphical image will not compress well in zip format and you will get a HUGE file.

Image Sizing:
Check Resize to fit width & height
uncheck Don't enlarge
Set your width & height to 9000 x 7200
Resolution: 75 dpi (this can be set to anything as it's a meaningless number as far as the file contents)

You can fiddle with the other setting as you see fit.

If you save as a jpeg, you can email it.
If you save as a TIFF, you will need to hand carry the file to the printer on a memory stick as the file size will be too large to email.