Nice deck, vampires look very fun with the new rivals of ixalan cards.
For the suggestions you requested:
I ALWAYS try to have only 60 cards - sometimes I really want to include a few more than 60, maybe 61 or 62, but I know that means I need to cut the worst 1 or 2 cards to make sure I have optimal chance to draw my best cards.
To find places to cut down to 60, look at dropping to 2x
call to the feast, 2x
queen's commission, and 2x
gruesome fate. That would get you down to 59 cards - add a 3rd
moment of triumph to protect your most important vampires.
To specific cards, the
Forerunner of the Legion will allow you to find any of your 5 drop bomb vampires, so would not need as many copies. You could add more Legion's Lieutenants (go up to 4?) that would pump your whole vampire army; your opponent will also try to kill them often, so the more the better
A flying
lifelink might be better than the menace vampire - its is more likely your opponent can double block a menace. Flying is better evasion to make sure you attack with a vampire each turn to trigger mavrin fein and get a token.
If budget is not a concern,
concealed courtyard would help with those double color casting costs, and
vraska's contempt could protect against planeswalkers or gods while gaining a little life. A 2nd copy of legions landing instead of the 3rd viscous Conquistador?
Thanks for sharing your idea!