Which one is which?

This is my '72 Sport

Given that most Belletts are lowered in front, including mine, without actually measuring anything, is straight better?

Steering arm angle (be horizontal or not) makes no difference. They can be vertical with 8 twists and turns and still work, but what is critical is where the small ball joint is mounted to the steering arm in relation to the upper and lower ball joints. That's where problem begin with bump steer and all sorts of issues.
It's the same on the inner end and where the steering knuckle on the end of the race is located in relation to the upper and lower control arm mounting points.
That's why I cringe when I see people start moving racks, inner mounting points, ball joints, spring rates, lowering amounts and God knows what else when they obviously have no idea what moving those things does to the basic geometry because it can be bloody dangerous.
I said as much before but it falls on deaf ears sometimes.

I am retired now but refurbishing steering joints tie rods and ball joint was my main business for many years. I still have my gear so if you are stuck you can call me I'm sure I could help. 0408 752 070. For rubber boots try Repco