This tool Power Brake Booster Tool - https://www.classicchevy.com/power-brake-booster-tool-57-397920-1.html?adpos=1o5&scid=scplp57-397920-1&sc_intid=57-397920-1&gclsrc=aw.ds makes adjusting the push rod on the booster simple. I think the nut size is 7 mm and needle nose vice grips help with...
The FJ60 has a proportioning valve located under the master cylinder, but no LSPV. The FJ62 does not have the prop valve like the 60, instead it has the LSPV at the rear axle.
I am no automotive engineering expert but in my long-term experience in driving Land Cruisers this sounds like...
Ignore this video. A 60 series booster replacement is not that bad. Some under the dash contortions and aligning brake pedal connection but otherwise not bad.