Remove Legion, add another squad of Sternguard.
Take the Combi Flamers from existing Sternguard and give them to the new squad.
Remove the heavy bolter from the Sternguard, the normal bolters are superior (special ammo
FTW). Likewise, remove the Power Fist, they shouldn't be in
CC. You want to wreck and/or break entire units with your Sternguard, not get slaughtered in
CC. If you charge inferior troops in
CC you will still win, you are marines after all (I'm talking weakling fish'eads and non-blob guard etc).
This takes advantage of Pedro's abilities and grants you far more flexibility with two scoring Sternguard units.
Take two squads of Devastators to take advantage of the IF tactics. Make one of the
Dev squads Lascannons, the other Missiles (with Flakk). Consider combat squadding the
Dev's for pseudo split fire; giving 2x 5man squads with 2x Lascannon, 2x 5man squads with 2x Missiles.
Add a
TFC, this will give you your ignores
LOS/cover where you need it (4x small blast templates sniping pesky
JSJ Tau
FTW, Pathfinders just ask for pain from these too.. don't forget about sniping weak characters like Ethereals to gain an extra
VP).
Remove the Multi Melta's from the Tactical Squads because you are going to be snap firing if you move the Rhino's.
How do you pay for all this?
Remove one of the
Tac squads (you shouldn't need it).
Remove both tanks.
Exchange
Tac squads Rhino's with Drop Pods (possibly with Deathwind Launchers). Nothing more annoying than pie plate AV12 pill boxes sitting in your opponent's deployment zone.
Veteran Sergeants are a waste in a shooty army because you shouldn't be in combat, and you haven't given them any melee upgrades, remove them. Take combi Melta's on the vanilla Sergeants, and replace the Flamers with Melta's.
You don't need Flamers with Bolter Drill (preferably take the 3rd coy IF tactics Close Range Bolter Drill, it's vastly superior if you plan to operate in Flamer range
imo, though you still need to contend with cover).
Alternately, consider Combi Plasma and Plasma Gun on your Tactical squads for the AP2 if you need it (pseudo split firing Devastator squads will hopefully ruin all of your opponents armour). Use Plasma on light transports at a pinch.
That's fluffy
CF/IF that fully utilise chapter tactics and Pedro's abilities.
I can see where you're going, mechanised Marines. But that doesn't take any advantage of the best special rules you are trying to use here
Hope that helps a little.
Edit:
Have to agree with previous poster, Terminators should be used as a heavy melee obstacle of sorts.
TH/
SS FTW.. Teleport them back field and watch your opponent sweat. Cheese it further with a teleport homer attached to whatever can carry one (likely a
Tac Sgt). They should be able to weather most of what is directed at them, and at the very least take a
lof of heat off what is actually doing most of the killing.