You’ll need a set of 4+2 tuners if you go that route. You can’t just rotate two tuners from a standard set and hope it will work well. You want the string tension to pull the round tuner gear against the worm gear, and if you rotate a standard tuner the tension pulls the gears apart, not together. The effect is more immediately noticeable on smaller diameter guitar tuners than good quality bass tuners which have a much wider post, but engineering-wise, the correct way is far better in the long term as the incorrect-way tuners will wear out far faster than the tuners with the correct orientation.

You should still be able to arrange the tuners for a straight string pull if you play about with paper and pencil. Given the relative thickness of bass strings to guitar strings, you’ll find that to get equal distance between the outside edge of each string, there’s a noticeable offset between the centres of the nut slots on a bass. You can’t just draw the centres of the slots an equal distance apart.

It is better if you can get the strings pulling in the line of the strings along the neck as much as possible. That way you only get the string pulling against the bottom of the nut slot, not the bottom and side. You need to consider the 3D force vectors. You get less overall friction, and less is better for tuning stability. A well cut nut slot can minimise friction, so you can get away with some splaying of the strings. But if the slot isn’t smooth, excess splay angle will exacerbate this, and you could find it hard to get the string in tune to start with, and then find it’s more prone to slipping out of tune when playing.