heavy bolters really are not effective against the nid swarm.... because they almost always get cover saves, making them not really effective. Lysander isn't really a super efficient
HQ for this, either... consider, would you rather have 5 more terminators, or lysander? Most often, 5 terminators are better. I know you HAVE to have an
HQ, so I suggest a librarian... the psy hood is amazing vs nids, because so many of their units rely on psychic powers (tyrants, zoans, tervigons).
The real key to beating tyranids is to pack a TON of missiles / lascannons, as well as flamers and bolters to deal with the little ones. Land speeder typhoons are ideal for this. I'm not sure what models you have, but a list that would annihilate nid players at 1500 points would look like -
HQ- Librarian (might of ancients + avenger)
Elite - 5x sternguard (2x combi-
plas) in razorback (Las/
plas) - 210 pts
Elite - 5x sternguard (2x combi-
plas, 1x combi-flamer) in razorback (Las/
plas) - 215 pts
Troops- 10 man
tac squad (flamer,missile launcher) in razorback (las/
plas) - 245 pts
Troops- 10 man
tac squad (flamer,missile launcher) in razorback (las/
plas) - 245 pts
Troops- 10 man
tac squad (flamer,missile launcher) in razorback (las/
plas) - 245 pts
Heavy- Predator (2x
LC+
AC) - 120 pts
Heavy- Predator (2x
LC+
AC) - 120 pts
yea, the nid player would take a pounding from 9 lascannon shots and 3 missile shots per turn, blowing away his monstrous creatures... if he gets in close, you have 5 razorbacks with flamers in them (the libby rides in the sternguard unit's without the flamer) to bbq them, and if there are any monstrous creatures left at that point, your razors have 5
TL-plasma guns that can rapid fire them down at close range.
Of course, this is pretty different from your originally posted list, but its what i'd take if I was tailoring a list to kill nids
edit - without a list of models available, I can't really tell you what list would be best for you :(