Theorycrafting and personal thoughts

Hello everyone my name is Loyalty4L I am a Kog'Maw OTP and I have over 200k mastery on him the main problem being with this guinsoos first idk what part i should go back to buy first the longbow for more attack speed the pickaxe or more ad or the blasting wand for more damage on his w to be honest i always do grab longbow first but what item next it is just so different now and is guinsoos even worth grabbing over botrk first? i mean botrk first is more for kogs survival in lane phase then anything I need help and normally I do not ask for it so this is a first step for me