That would be fine. One thing to remember about Tessco is that their normal pricing isn't that good, you'd likely find a better price elsewhere. I have gold pricing through Tessco, and the price is $11.47, so you would be really getting hosed if you paid the list price on that. Second thing is that Tessco has a $50 minimum order, or you will pay a surcharge on top. More hosage.
The brass, zinc and stainless steel doesn't make that much difference unless you are really close to the ocean or other corrosive atmosphere. The brass will work fine for you with a little bit of maintenance, which you should be doing with NMO mounts anyway. Stainless gives you some advantages and some additional costs.
The pre-attached BNC connector can be a real pain in the butt when you are installing this. If you have to run the cable through any tight locations or through a firewall, you've now got a big BNC connector on the end to deal with. Having just the cable itself to run makes installation easier in some instances. You might not have a problem at all with this.
One thing you can do is look for the mounts with a pre-installed FME type connector on the end. They are smaller and will route easier. When you get it all installed, you simply thread a special BNC adapter on the end. The FME to BNC adapter will cost you a few bucks. Ideally, you want to avoid additional adapters, but as adapters go, the FME models are quite low profile and are not as bad as having stacked adapters.
As for the cable, RG-58 stranded center conductor will have slightly more loss in the cable run, but will be more flexible. More flexibility leads to easier installation, tighter bend radius, and less chance of the center conductor migrating through the center dielectric (insulation) and causing issues. The solid center conductor RG-58 will have less loss, but be stiffer and harder to run.
Sounds like you are not interested in having a shop do the installation, so here is what I'd recommend:
If you purchase through Tessco, you will pay more. You'll also have to deal with the $50 minimum surcharge.
Instead, check on HRO (
Ham Radio Outlet - World's Largest Supplier of Amateur Radio (Ham Radio) Equipment. Sales, Supplies, and Service.) or AES and just purchase what you need. Get the brass NMO mount with the stranded center conductor RG-58 with the FME connector on the end, this will ease installation. Purchase the FME to BNC adapter and be done with it. For a scanner install, don't get too hung up on the feed line losses. You won't notice a few tenths of a dB difference in your install.
Down the road, make sure you remove the antenna from the NMO mount periodically and check for any corrosion underneath. Clean the mating surfaces and make sure the seals and O-rings are in good shape.
When you run the cable, be very careful to keep it away from sharp edges and don't let it get pinched or bent to the point of getting a kink in the cable. If you do use a mag mount, trunk lip mount or an "L" bracket from the side of the trunk or hood, be real careful about where the cable runs through pinch points.
