Here's the tanks, tanks can be a bit risky, esp if there are no pics of the inside. A lot of bikes seem to get left out in the rain in japan and you see a lot with rusty insides. Remember post won't be cheap either
http://translate.google.com/translate?prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fpage21.auctions.yahoo.co.jp%2Fjp%2Fauction%2Fj21956503&sl=ja&tl=en&history_state0=
http://translate.google.com/translate?prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fpage15.auctions.yahoo.co.jp%2Fjp%2Fauction%2Ft105081313&sl=ja&tl=en&history_state0=
http://translate.google.com/translate?prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fpage.auctions.yahoo.co.jp%2Fjp%2Fauction%2F114130744&sl=ja&tl=en&history_state0=
http://translate.google.com/translate?prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fpage12.auctions.yahoo.co.jp%2Fjp%2Fauction%2Fp131620960&sl=ja&tl=en&history_state0=
Cap won't be a problem, they're fairly generic of Honda tanks of that age.