Yea, 70-75 is fine for LP applications with the exception of the SPG spool, that is also 70-75.
With the exception of the tank face orings, all orings should be lightly lubed with one exception, the spool oring. Be very liberal with the lube on it, esp in the void between the hose end and the SPG. Basically, you want to fill that void with lube. The reason is the area between the hose/spg and spool will get water into it which is impossible to flush and will remain there building up salt as it slowly dries, that extra lube acts as a corrosion barrier and as a filler, preventing water from entering the space and or SPG from corroding with the spool.
With the exception of the tank face orings, all orings should be lightly lubed with one exception, the spool oring. Be very liberal with the lube on it, esp in the void between the hose end and the SPG. Basically, you want to fill that void with lube. The reason is the area between the hose/spg and spool will get water into it which is impossible to flush and will remain there building up salt as it slowly dries, that extra lube acts as a corrosion barrier and as a filler, preventing water from entering the space and or SPG from corroding with the spool.
