Gunblade is good for the champions that can use all the stats and it's a pretty good item overall for these champs, very cost efficient.
Revolver though, is pretty meh. It's ok, kinda, but I feel you're better off buying it later when it actually spellsteal a decent amount, or never and just get tanky items instead(for example a randuin's omen, gives armor and health, slows people attacking you, gives you another AE slow for after your pool). It's almost never gonna save you, it only delays your death a bit, and not at all if you get focused first heavily, it's good over time only, which Vlad doesn't really care about since you already can Transfusion to heal over time. Also apparently it's bugged on Vlad because of the Rylai balance thing on Transfusion, so it only drains as if it was an AE(so like 4%), until next patch. If they made will of the Ancients good, it'd be worth buying, but atm not really, it's not very good early game, and late you probably want a better item in the slot.