First off let me just say that I don't think I've ever been more in love with a deck concept than I am with this! I was seriously just thinking about doing something with sakashima and ravos for clones so I really love that I saw this! I'm gonna break this into sections for your convenience.
Draw- If you're looking for more/better draw options, you can never go wrong with staples (assuming you don't care much about the budget). So
phyrexian arena,
rhystic study,
mystic remora, and
dark confidant are all fantastic choices. Arena and confidant both cost life but that's irrelevant if your entire strategy is gray merchant (arena life loss is minimal anyways), they also help out with devotion. Rhystic and remora are just outright good.
Clones-For clones specifically I'd recommend adding in
evil twin as a more versatile option instead of maybe
clone or
wall of stolen identity. Wall is better if you don't ever want to attack under any circumstance, but
clone is better if you want to copy something like an ulamog and just wreck
havoc. Also might
consider helm of the host if that's your thing but I'm not sure if it'd be better or worse than another
clone creature in this deck.
Tutors-I'm not sure how many tutors you're looking to use necessarily, but here's a few more worth considering:
mystical tutor-gets better tutors, removal, or counterspells
Enlightened tutor-gets good draw enchantments like ones listed above or especially
necropotence, value artifacts, or even ramp in the early game
Profane tutor-a decent 2 mana tutor but pretty annoying to have to wait to pop off
Spellseeker-great for fetching other tutors or removal, and an amazing blink or
clone target for value
Diabolic intent-maybe good if you're willing to part with a creature since you have ravos but probably not great in this type of deck
There are also budget options for this category but in most cases you'd probably be better off just paying an extra mana for a
mastermind's acquisition or something if you go that route.
Lands-Lands are huge for any deck so if you've got the budget for it definitely don't skimp out on them! I personally recommend the battlebond lands unless you play mostly 1v1 games (which partners are technically banned in unless I'm mistaken).
Shock lands and check lands are also pretty much always good choices.
Reflecting pool,
exotic orchard, and maybe even
path of ancestry are good choices as well. The biggest thing in my opinion though is definitely gonna be
urborg, tomb of yawgmoth and
cabal coffers. Love it or hate it, it's some insane mana generation when it pops off!
Bonus-I got tired of typing so here's some other good stuff to
consider that didn't really fit into a category listed above but is definitely worth a look: lim-dul's vault,
phyrexian reclamation,
land tax,
generous gift,
anguished unmaking,
damn,
winds of abandon,
counterspell,
swan song,
mana drainWell anyways I don't know if this helped at all but I hope it was at least slightly beneficial to you. No idea why I decided to write all of this, but I'm glad I did. You've got an awesome idea here and I absolutely love it! Best of luck with the deck bro!