For the Nixie 3, perhaps go for two MCL in the MG and then make use of the extra space with more mobility, since a pair of MCL is better than a single LCL in everything except range. Having only 3/5 movement and no JJ makes it rather harder to use, and a switch to MCL would require speed to make full use of them and to differentiate it from the Sprite 3.
I'll go look at the Lindwurm when I get back home in about four hours.
Since you've gone to the trouble of getting art for it, have you got a TRO-style fluff writeup to go with it?
I have the notes, but it not yet complete and open for change. But to give you an idea.
The legal iHLL and LPL versions are the PR1 and PR2 (prototype versions) respectively.
Then comes an omni-version, that goes off the rails as it were, with custom tech.
The Prime and A follow the earlier versions. And then there are:
Alt-B: iHAG-10
Alt-C: LRM12x2
Alt-D: Nova+ERLL (mentioned with notable section)
[EDIT]
You know, since there's nothing (IIRC) against it, why not a protomech with Angel ECM?
Indeed why not, there is plenty of tonnage for it. About 6500 kg would remain, a pair of Streak launchers would be a good fit. (Alt-E?)