7.62 is just the bullet itself... 7.62x54R 7.62x39 7.62x55 {30-06 7.62x51 {308 win} so your 17 in the original .30 1906 should be legal.
the 303 {.311} is used in many..7.7 Jap, 7.65 Arg, .303 Brit, ect.
5.56 is .{.223} or {.224} used in many many rifles, from .22 Hornet up to .22-250..i would look a little more into the rules they have set..
i know that in many European countries they have banned the ownership of rifles chambered in any military cal..so many shooters have made them in wild cats../30 gibbs, 6.5-06 ect..
if your loading your own, then your can load the 30-06 pretty hot, and pretty darn accurate.. the long magazine box on a 1917 makes feeding a shorter round pretty tough unless you modify the folower, spring and box.