Anybody have recommendations of a smaller high efficiency (92+ AFUE) gas forced air furnace around 60k BTU ?

Wondering if there was ever a catalytic heater designed for central forced air heating?

I have a 20+ year old Lennox 100k BTU G20R type furnace and there has been rust damage to the burners from a sneaky leaky roof in the utility room. For my small abode 100k BTU is overkill. Thinking it may be possible to retrofit a catalytic heating element where the burner would ordinarily be. Still doing my homework. Are there catalytic heaters designed to direct heat upwards? Can catalytic heaters be converted to natural gas? Then there's the whole controls issue, tying in with the thermostat & blower (which is probably inefficient by today's standards).