Lord Commissar
Powerfist
Platoon Command Squad (useless but there we have it), if only they could merge too.
Infantry Squad, Lascannon
x2
H/W Squad, 3 Lascannon
x2
Conscript Squad
545pts
The platoon squad can go commit suicide
The rest can mob up, so we have a 53 strong squad, with two challenge soakers, a moderate MEQ killer, 34 bullet catchers and 8 lascannon, that is unbreakable.
545pts
Or perhaps 8 autocannons for 465pts (autocannons are as good at tank busting as lascannons, except AV14, and the damage table is slightly poorer)
It cant score, but it can contest, it can put out a load of High S shots and it can tarpit for at least three phases (two sergeant challenges and then the Commissar with 10 or so rerolls on his refractor)