I sourced the extension brackets from Japan many years ago. There are several companies that offer them, these were manufactured by Zeal. You can try asking @sonk76 , as he purchased them more recently from Japan4x4. The 80 series springs and 30mm spacers were to accommodate the extra weight. There are many options to get the desired ride height/AHC pressure. (non-AHC 100 springs, LC80 springs---two DS or two PS, as they are different in height, 10, 20 & 30mm spring spacers.)
60mm Rear Brackets (shows 4, only 2 needed) 5000 Yen/pr:
View attachment 1055127
40mm Front Brackets, 6000 Yen/pr:
View attachment 1055128