For the current v0.7.3, make sure you try both Azimer's 0.40 beta and both the 0.30 drivers, JFG has some complicated sound effects that require the best plugins to emulate correctly.
When v0.8.3 is rereleased, you could always try PJ64's RSP LLE plugin for LLE of the sound, which should solve most sound emulation issues in 1964.
FYI, I'm using Azimer's v0.40b2 with Enable Audio Fix and Stop sound when paused checked, and buffer size left at default. This works for me in JFG.