Yes and Yes
You can get generic battery cables at about any auto parts store and use those for cheap. They usually run too long but you can find the shorter ones usually marketed for lawn tractors and such, especially at big box stores (Wal-Fart and such). If you have to have OEM, they are about twice as much:
Positive cable:
CABLE 32601-MG9-000 about $18
Negative cable (cable only):
CABLE 32401-300-010 about $16
The Honda OEM switch is "
SWITCH, IGNITION 35010-315-017", about $53 and readily available at numerous Honda OEM parts suppliers like:
Honda Direct Line
Honda Parts DirectThe above both also have free, online parts diagrams with numbers listed
(see picture below-parts numbers are in the price charts), so you can answer questions like this in the future, for your self or others. These quotes are all for the '71 CB750, by the way.