I understand if you wanna model him in Terminator armour, but unless you are planning on DS'ing him, I would leave it off. Power armour looks just as cool, and is easier to justify (I have no doubt Terminator armour is rare outside the Astartes). I would also drop the Acolyte, power weapon and familiar.
Elite is awsome, I hadn't really considered using Eversors and Death Cult like that before. Might do something similiar myself, when I get bored with my Vindicare...
If you really want lascannons, and don't care about losing them to enemy assault troops, Inducted Infantry Platoons can add bulk and heavy weapons at the same time. Macharian Cross gives you way more tactical flexbility than Marines. And, you won't feel as bad when you lose them to enemy fire. They cost 40 points more than your Space Marine idea, but you get another lascannon and more than twice as many ablative wounds. They also look more synergistic with your Stormtroopers.
Stormtroopers; I dunno, when I play defensive with dual plasma I generally either get assaulted and slaughtered, or I am out of range for much of the game. A 5-man assault squad with meltagun and plasma gun, packed into a heavy flamer Chimera with smokes+extra armour, can form a powerful spearhead unit. Backed up with lascannon fire, you should be able to punch a hole in the enemy lines.
If you take Imperial Guard in Troops, you get access a Sentinel squad and a Leman Russ. I would argue they can be more effective than your current FA+HS selections. Leman Russ with hull-heavy bolter is cheap and can lay down powerful blasts, Sentinels with autocannons can support your Stormtrooper assault with anti-infantry dakka from long range.
So, after all that, here is what you might be have (you can always go with Marines if you feel it suits you better).
HQ
Inquisitor Lord, psycannon
3 x heavy bolter servitors
Sage, Mystic
(166 points)
Elite
Eversor Assassin
(95 points)
3 x Deathcult Assassins
(120 points)
Troops
(2) Junior Officer, Macharian Cross
4 x Guardsmen, lascannon
3 x Infantry squads with lascannon
(255 points each)
(2) 5 x IST's, meltagun, plasma gun
Chimera, heavy flamer, extra armour, smokes
(158 points each)
Fast Attack
3 x Sentinels with autocannons
(150 points)
Heavy Support
Leman Russ, battle cannon, hull-heavy bolter
(145 points)
Total; 1,502 points