I'd like to think your estimates are accurate, but when I check the facts here...
http://starwars.wikia.com/wiki/Battle_of_Yavin/Legends and here...
http://starwars.wikia.com/wiki/Battle_of_Endor/Legends
I see something a little different...
• MC80 Home one type Star CruisersHome OneDefianceIndependence1 Unidentified• MC80 Liberty type Star CruisersLibertyMariaReef HomeNautilian• MC80 wingless Liberty type Star Cruisers• MC80a Star CruisersWhich can be eyeballed to be about 12+ in the movie
• Smaller Mon Calamari Star Cruisers• Destroyers• Carriers• Dreadnaught-class heavy cruisers• ManowarsUnknown number of these ships.• Neutron Star-class bulk cruiserUrjani• Quasar Fire-class bulk cruiserFlurry• 10+ EF76 Nebulon-B escort frigatesAntares SixRedemptionRemembranceValianceYavarisPatiencePromise• CR90 corvettesEridainMasanyaNovaFlareOld RepublicPushtiSakiUlletThese are only the known CR90s. The ones we don't know the name of aren't listed.• DP20 frigatesChandiEnsaiavGhorman's HonorMastalaTelsorWalervDukeDoomSteadfastSame thing as with the CR90s• GR-75 medium transportsLimnateLuminousTuimaSame ^^ Especially as there are at least 20 of them visible in the movie.• Braha'tok-class gunshipsBraha'tokTorktarakThere were in fact only 2 of them.• Tankers• Alderaanian gunshipsUnknown number.YT-1300 Millennium Falcon
Skyhoppers
Cargo freighters
Imperial Shuttle Tydirium
Starfighter squadrons88th Attack Squadron94th Fighter/Attack SquadronAggressor WingAmber WingAzul SquadronBandit SquadronBlade SquadronBlood SquadronBlue 77 SquadronBlue SquadronCasper SquadronCobalt SquadronCorona SquadronCracken Flight GroupCrimson FuryCrimson Phoenix SquadronDagger SquadronDantooine SquadronDeretta DestroyersDragon SquadronDust SquadronEcliptic EvadersExeter SquadronFeral GroupFlying Bantha SquadronGavial SquadronGold DevilsGold SquadronGray SquadronGreen SquadronGrez SquadronGriffon Flight WingH-Beta SquadronH-Delta SquadronHavoc SquadronJyn Freila's squadronLightspeed PanthersNightmare SquadronNomad SquadronOro SquadronPhoenix SquadronPlasma DevilsRampant SquadronRascal SquadronRed SquadronRed TeamRenegade FlightRogue SquadronRust SquadronScavenger SquadronScreamer SquadronShandor SquadronShark SquadronSoaring DactillionsSpecter SquadronStar SquadronStealth SquadronStorm SquadronSundancer SquadronTierfon Yellow AcesTiger SquadronTwilight Squadron (defected)Ulan SquadronViper SquadronVortex SquadronWolf SquadronYellow Squadron
67 * 12 = 804 fighters.
I think, this fits my numbers pretty well