Would definitely scrap the reavers for something else, to be brutally honest. I run that squad (3 with lance ) occasionally, and it's never been better than "ok" at best.
My next suggestion is assuming that you're playing as a doubles match (i.e. both on the same table at the same time), so if you're not doing that then please disregard the following:
I'd be tempted to even get rid of the ravager as well, and focus on anti-infantry. Necrons get really good access to anti-tank, so you could leave the anti-armour to your friend, and really focus on jamming as much splinter weaponry as possible into your list; if you dropped the ravager and reavers, you could get a venom with extra splinter cannon, filled with 5 trueborn, 3 with shardcarbines and 2 with splinter cannons; at 18" range that pumps out a colossal 31 splinter shots between them, 12 of which can be fired at a separate target; cutting the haywire grenades from the archon plus the points you have left would mean you could get him a PGL, handy with incubi.
Doing so would give you an absolutely BRUTAL amount of anti-infantry firepower in the form of 12(!) splinter cannons in the list, plus a couple of nasty c-c units in the incubi and beast pack. You'll have no problems dealing with enemy infantry, and you can get the necrons to deal with enemy armour.