William,

Don't hack it up, its a nice example of a bike boom era
bike. Nishiki were really nice bikes, the problem came when
they started marketing to dept stores and their reputation
nosedived.
What kind of components are on it?
What kind of tubing (I'd venture a guess, Tange tubes).
I'd agree that the plastic ends are for a frame pump.

The Kokusai model became the International in 1973 so
I'd say the bike is early 70's minimum. It was a mid level
bike in their line up (below Pro and semi-pro models).
There were some Nishiki frames that were Colnago
produced and branded with Nishiki stickers. I'm trying
to get info on those, they were marketed by Bikeology
in Ca. I believe (and this is verified info) I'm thinking the
model was maximum or something similiar?

Marty