I believe those arms were basic LT arms modded with perches. I may have some old messages from him and I’ll see if I can get a brand and name on who modded them for the additional perches.
In the end if you’re picking a length, decide on whether or not it’s a dedicated street cruiser or if you intend on taking it to the track. If you’re doing track days, I believe many classes of mortad racing allow 52 inches wide or 132cm.