I own that arm, got the specs, installed it myself, absolutely love it, I'm sure you will also.
you are correct: 225mm spindle to pivot 15mm overhang 240mm effective length null points 60mm and 117mm
others: there is a mint one for sale now https://reverb.com/item/53590531-acos-lustre-gst-801-tonearm?gspk=SGlmaXNoYXJrLVJldmVyYg%3D%3D&utm_campaign=Hifishark-Reverb&utm_medium=affiliate&utm_source=partnerstack-legacy
sumiko’s ’report’ is amazing, you can download it and the owner’s manual from vinylengine.com (join if not a member, it’s free)
the anti-skate is best set by watching the arm on a blank disc. this disc has overhang and null point lines for any turntable/cartridge, and other blank side to set anti-skate
spin platter by hand, lower arm, adjust dial (it’s activating a magnetic force, magnet is many years old) come back in 20 minutes, double check it. then I usually double check tracking and anti-skate every month or two.
note the big heavy round ring that mounts below the plinth. it is a terrific counter-weight. NOT a nut, it is smooth round, with a few holes in it’s edge. you need room to get something in the hole you can then use to tighten it.
You could drill a few holes in it’s bottom edge to get something in to tighten it if you don’t have side clearance in your plinth. Think ’symmetry’ when drilling holes to keep it balanced, not critical, but we are perfectionists