Here's an interesting question, is it safe for me to use a 53 watt halogen bulb (designed to replace a 75 watt incandescent) in a lamp that is rated at 60 watts maximum.  I'm interested because a Philips 53 watt bulb is 790 lumens (dim even for a classic 60 watt incandescent). 

The 60W GLS put out something like 2W in light and 58W in heat+IR combined, so sure the 53W lamp can't exceed that. But question is, how does it's output split between heat vs. IR compared to the GLS. (i don't expect a difference dramatic enough to cause problems though)

It really depends on the exact lantern design and what is the limiting factor.
Generally the safest way is to not exceed even the "equivalent" rating.

A common 230V 100W incandescent emits about 10W in convective (plus long wave IR; 10um and longer - the part that is absorbed by the glass) heat, few percent in visible light and the rest as a short wave  (around a um, so passing the glass) IR radiation.

The halogen capsule is rather large object heated to not that high temperature, so relative to the same power input it radiates more power in the long wave IR and so consequently dissipates as convective heat. But due to the higher efficacy, I think the convective heat will be not be higher than the equivalent light output lamp.

So if a fixture is open for the short wave IR (e.g. a glass globe), it will be limited by the convective heat within the globe (the 10W) and so you can not use more powerful halogen than the "100W equivalent".

If the fixture is limited by the short wave IR load (e.g. paper shield,...), the same input power rating should be fine too.