Referencing the NSW Govermnet Spacial Map Viewer portal, shows the highest official reference point, closest to the observatory, is at 1454m AMSL (Above Mean Sea Level)

On-site assessments of the immediate surrounding topography, puts the levelled ground, at the site of Eagleview Observatory, several metres below this high point. However, the
telescope optical tube assembly is a bit over 2m above ground level at the site of the observatory. Considering these references, the best estimate for the height of the Optical tube
assembly, is likely at or close to, 1450m above mean sea level.