You can get the game sfx by running a level in WinUAE, then saving an *uncompressed* save state. Then import this as raw signed 8-bit audio (rate is 8/11Khz?) into your audio editor (e.g. Audacity).
As for game music, I know Swirlything converted a load of the CE musics into Screamtracker format if that helps, you can get the packs from AMP -
http://amp.dascene.net/download.php - scroll down to 'Converted Synthetics' section - see RJP (2nd review) for the latest versions of those.
I would also hope that if you are given the green light by Mike M after seeing your proof of concept that he may be able to provide you with all the original game assets - if he still has them, so that you can finish your remake 100%.
Q;