ok, here are a few questions:
The 75 FT cable run, is it mostly vertical up a tower or along the ground? how high is the antenna above ground?
Will there be any adapters, couplings, splitters or other lossy connections along this coax run?
What are you using for an antenna?
What kind of connectors will be used at the back of the radio and at the antenna feedpoint?
What kind of noise sources do you have near where the coax will be ran, things like motors, floresent and neon lights and computerized equipment?
What is your budget?
obviously you will want to use the best coax you can afford, but you also need to look at the costs of connectors to fit that type of coax and where it will be installed. i use 213 with my equipment, but its only a 40ft run to the antenna. You can get by just fine with the 213, but buy a good quality such as belden or times. Mini 8/RG8X is a bad choice, its nearly 3 times the loss of real RG8. Radio Shack coax is typically poorly shielded and lossy, avoid that too as well as RG58. Basically, look for a quality RG8/213 or something like the LMR400 or the Belden 9913. Compare the loss of the various cables and see what cable will provide the least loss within your price range. Also look at the costs of RF connectors for the various cables, PL259s are generally cheap, can be had for as little as $.99 each, but you will want to use a teflon insulated silver coated connector, so expect to pay ~$5 for each connector, and more for the "N" connectors that are commonly found on commercial band antennas. if your radios have mini-UHF or a small connector like that you will have to factor in the cost of adapters and other accessories to convert from the large diameter coax to the small diameter connectors. many commercial band mobile radios use the mini-UHF and TNC style connectors, a good quality coax will be larger in diameter than the connector on the back of the radio so in many cases an adapter has to be used. Hopes this helps.