All things considered, I think it was the best strategy i could have come up with. ...even though most of my time between repeated attempts was either obtaining more copies of my combo pieces or throwing out cards that bloated the deck, and virtually every turn I took involved a multitude of game actions involving anywhere from 2-5 drinks within a single turn, many of which gave little to no progress toward securing a significant enough negative life total to stall until I could shuffle into my low card count for Pact.
Then again, as far as I know, the only way to get extra copies of Pact or any consistency tools besides Sisyphus was in the second half, so I'd say I managed to make it as consistent as I reasonably could have. I never did a second run to try out a more intended Origin Of The World build, so I can't say anything about the consistency of that strategy, but I felt like what I was actually doing in the battles was relevant enough in the in-between turns was doing something to get me to my win condition, even though it was very little.
A lot of how the deck succeeded relied heavily on game rules. I had a ton of dump-whole-hand-to-do-nothing turns where i just stabilized my lust to just one or two points above 0 after the turn shift, and the custom draw engine and shuffle system is truly what made the deck shine. Being able to rely on drawing upwards of 3 cards consistently each turn was a make-or-break mechanic, and knowing that I couldn't deck out because draws weren't forced is one of the things that got me to commit to Pact stall in the first place.
Also, I didn't mention this before, but the story beat at the halfway point was a great twist. Getting people to think they're about to get the one thing they "won" the game for and pulling the rug out from under them while delivering more than that in follow-up stages was a really nice touch.