I tried something simliar recently, the Marvic float locks, which basically convert any float into a "Polaris" or Dave Thomas-type design.
Can't say I was thrilled to bits with them. It's right it sits up perfectly "on-depth" but I found you need to use a lot of lead on your line and I usually just rely on the weight of the bait and three or four swanshots.
I also found the floats gradually crept overdepth and kept keeling over and giving false indications when fishing in a chop.
The "traditional" rig of a pencil float set a foot or two overdepth, fished on a tight line still takes some beating.