You want the one for 27.0MHz. Shorten it by 10mm and you're good to go. About 1040mm should be about right for approx. 27.205 which is the center of the CB band. If you look at the difference from 27.0 to 27.5 I just split the difference and go with it. Or close to it. If memory serves me right I tuned mine at this tip height. 1040mm should be about perfect. The radials are all the same and they give you the length to place the radials at. I just use a converter app for making MM into Inches. So 1040mm would be 40.944 inches. The radials don the same and use a sharpie to mark your lengths. Also use some blue loctite in the Allen screws that hold the radials and top whip. Tnis will keep them from backing out over time. Also if possible get yourself some no-ox special "a" for all connections minus the coax connector. Place some on all the self tapping screws and at every section where they screw together. You can get the no-ox off eBay for pretty cheap. Under $10. Here is what I am speaking of. See pic below for no-ox.

Use just a very light coat on all screws and such. Don't use on the Allen heads as they are stainless and you will be using blue locktite on these screws which should be 9-10 of them total. You'll see when you get the antenna where to use it. Any Allen screw that can back out over time with being moved around and such. Don't use the red locktite it's too much and you won't be able to get it loose!! Been there and done that!! Take your time, measure twice and double check all your measurements!! The antenna is light but will be a bit awkward to mess with. I suggest a 2nd set of hands to help lift the antenna up into place as to not bend it as the antenna is pretty long. Again you will understand more when you get the antenna. They are simple to put together and if you use the measurements I gave you for the tip you should be about good for tuning of the antenna. If the vswr is good on 1,20, & 40, leave it. Like a 1.1:1 or lower. The antenna should tune pretty flat across the 40 channels of the CB band. And as far as the coax goes, at least get a 100ft run of some rg8x or whatever you need to reach your radio room that is under 100ft. This is where the coax I mentioned comes into play. And if you look around you can get the coax for under $100 for 100ft. Try looking at Jefa Tech coax. The rg8x/LL240flex is $.43 a ft. That would be $43.00 for 100ft. Good coax and a good price!! Shipping shouldn't be too much. Add about $10 for shipping. Maybe a bit more. So for $60 you can have some quality coax that will last you a while and will work well. See photo below for Jefa tech coax as well.
Can you swing $50-$60 dollars for 100ft of some quality coax?? I'm sure you can dig up that much. Whatever you do, don't use the Radio Shack coax for your base station, it's not very good coax and I promise you will have issues, if not now then later, with the RG58 from Radio Shack!!
Don't skimp out on the coax and you can also have the connectors added as well or buy a 10pk of amphenol connectors like the ones listed below. Again, see pics.
You don't have to get as many connectors as shown but these are the ones you want for the coax I listed. And make sure the have the reducers. I use these connectors and have never had an issue with them!! The coax I've not used the Jefa Tech coax myself, but have been told by many it's quality stuff and well worth every penny!! Again, do it right once or have to take it down to mess with it a year from now or less is the question you need to ask yourself. I promise that the radio shack coax will in the end become an issue. Just not made for long term use outdoors like you want. JMHO. This is what I would do. Spend once and be done!! It is worth the extra few extra dollars to get quality parts and know they will last!! Again, JMHO. And your antenna "system" is the most important thing next to having a radio. Good luck and hope to catch you on air sometime.