I believe the PDF I attached above is for the flashboard / ROM board.
28F128J3A x 2 is the Flash chip by Intel.
K4S281632B x 2 is the 128Mbit SDRAM.
(You can buy this here in Japan for 299 JPY
)
https://wakamatsu.co.jp/biz/products/detail.php?product_id=17010435
As for how to desolder, a video is here on YouTube at:
(Time: 2:18
)
I've never desoldered surface mount IC chips before, only experienced in larger DIP ICs.
I think it's best to try it out on other chips first.