1971 Dart Swinger Worm Gear Adjustment

Some background on the car, it's a 1971 Dart Swinger, originally a slant 6 car, now has a 340. I purchased the car about a month ago and immediately had to do some front end work to it and so I've replaced everything major under the front end with the exception of the torsion bars, so that's new shocks, ball joints, tie rods, idler arms, shocks and tires.

That said I've still got 3 to 4 inches of play in the wheel. When running down the road if I don't make any movements it'll track straight but trying to make an adjustment one way or the other and the car wants to move quick.

Doing some research and found that, as a long shot I can adjust the worm gear(s) on this power steering gearbox and that could get rid of a lot of that play.

So, on my first attempt, I took out the battery and the battery tray but couldn't get a standard size box wrench with enough room to fit onto the adjustment nut, so I'm not even sure what size that nut is. I'm fine with going to pick up a set of stubby box end wrenches but I can't even find out what size it is, to make sure the set has the wrench I need. The headers barely offer enough clearance to get the screwdriver down to make the adjustment once I free up the adjustment nut. Does anyone know what size that adjustment nut should be?

Car is pretty much not drive-able at this point because of the play in the wheel. If I need to replace the gearbox and the steering shaft knuckle that's fine I'll bite the bullet and do it but this seems to be a possible solution, if I can find the right wrenches. Since I just bought the car from a reseller who just bought it to sell it, I don't have any frame of reference as to what kind of issues the previous owner was having with it.