IMO, nothing beats deficit deads, rack pulls from mid shin, SLDL’s, regular deads and front squats for building your deadlift. Get cock strong on those, and your pull will follow.
Are you of the notion that the quads are significantly recruited during the initial drive off the floor?
Are you of the notion? Seriously?
Start of a deadlift is mostly quads and glutes, which front squats will make “cock strong”.
As for pulling from a deficit, don’t pull from more of a deficit than you can get in position for. If you don’t have the flexibility or if it’s different form than how you’d pull from the ground, carryover will decrease. Even standing on 1 plate would probably help build even more strength from the floor.
If you want to get scientific about it, a movement can be strengthened up to 15 degrees ROM outside of the motion trained, so if a 1" deficit is within this 15 degrees, you’ll be strengthening the start. Even if you go outside of it, you’ll still be strengthening that portion since you’ll be going through that point, but not as if you were within those 15 degrees and starting the movement.
If you want to get less scientific and just get stronger (I tend to lean towards this option), pick a deficit height you are comfortable with and pull, get stronger, and cycle the exercises Hanley said.