I run a couple of 800MHz systems, and I have a few simplex channels in the radios. Working in heavily forested areas, I can tell you that range will be poor on these frequencies.
As others have pointed out, there are no "free" frequencies in the 700 and 800MHz bands. No itinerant channels, no CB/public use channels. Most of the spectrum is set aside for public safety users, some commercial users, and if these are pre-reband radios, cellular. Causing interference to any of those users will result in issues you don't need.
Even though those radios will run 3 watts transmitter power, you'll get much better performance from 2 watts on MURS, or even a couple of watts on UHF (FRS/GMRS). 800MHz isn't a good choice for this sort of stuff.