I’m not sure if the SWE version was included in the myspleen release (is it the 1993 LD audio?) but I think I’m just gonna settle with the optical for now, it sounds great!
The SWE is the Special Widescreen Edition laserdisc (the set - along with the Japanese Special Collection - that had the 1985 remix for ANH). It’s still the 1983 theatrical stereo (the same mix as the optical audio from the print that’s track 1 in 4K83).
Schorman says the best-sounding LD of the 1983 mix is the earlier US pan-and-scan LD, while hairy_hen is recommending the US Special Widescreen Edition LD for the same mix - neither is included in 4K83’s MKV or ISO releases, but Schorman has made 4K83 synced versions of these tracks (along with the Japanese pan-and-scan and Japanese Special Collection versions) available over on the 4K## forums.
The 1993 LD audio is a remix and not the 1983 theatrical stereo, which is why it’s also included in 4K83. ESB and ROTJ didn’t get remixes for the JSC/SWE like ANH did, but they did 1993 (and ANH got another remix).
Schorman’s recommendation for the “Best” '83 laserdisc audio is track 4 on the ISO. (It is not on the MKV, but is included in the Alternate Audio folder with the MKV).