Move the G saddle almost all the way forwards (looks like it is in the picture). Measure with a metal ruler from the G nut slot to the point on the saddle where the string will leave the saddle going towards the neck. This will be about 2mm back from the front of the saddle. Move the bridge so this distance is 34" /863.7mm. I'd put masking tape on the top of the bass and mark the front and back bridge position on it.

Then you can use ordinary string or thread running from the E saddle up to the E nut slot, through the tuner holes and back down from the G nut slot to the G saddle to position the bridge so the strings run an equal distance from the edges of the neck. Get the bridge sitting square to the neck and mark the edge positions. You now know where the bridge wants to go.

You shouldn't need ferrules on the top of the body. But your bridge is a bit different to normal as the string holes are normally round and probably a bit smaller. Your holes appear to be keyhole shaped (unless they are 'racetrack' shaped and it's the saddles that make the hole look narrower at one end), almost as if the string ball-ends are expected to be pushed into a hole beneath the bridge and pulled forward to keep them in place.

Could you confirm the string hole shape, maybe with a photo of the underside? The bridge itself should act as the support for the string when it leaves the body, but with an elongated hole, there is no definitive point to drill a hole through the body from. You'd want to put it at the front of the bridge hole, but with the E string saddle sitting further back than the G, the string may end up being too vertical or even come out backwards.

So I'd probably drill the through holes in the large part at the rear of the bridge hole, and maybe file at an angle with a round needle file at the front of the hole, so the string can angle forwards if necessary. You'll just have to accept that the string may cut into the wood a bit over time, but it will be stopped by the front of the bridge hole.

I don't know if this was an expensive bridge but if not, and you don't like the thought of an elongated hole in the wood, it might be worth looking for a different one, or just use this one for top loading.