Need to convert my Procom FBD400T fireplace for remote operation

SOURCE: Procom fireplaces

Empire makes a wall heater that is direct-vent that looks similar to vent- free wall heaters. Here is a link to a website that sells their products... http://www.mastersalesonline.com/empire/index.html. I am not sure of the prices you will need to call the on-line store. I hope this helps you.

SOURCE: convert a procom heater from propane to natural

you need to find a place that makes your type of heater and they will have a change over kit all it is different orfices and jetcovers for each gas jet from your heater its self explanitory once you see the parts,sometimes there are different gas comp. that if you use there service they will change you over at no or little cost. hope this helps

SOURCE: I have a ProCom FBN400TYLA vent free natural gas

Found the manual on line and copied directly from it:
WARNING
Models FBN400 are equipped for Natural
gas. Field conversion is not
permitted.
Models FBL400 are equipped for Propane
gas. Field conversion is not permitted

This should answer your question.
See if you can run the gas line or find someone to do it cheaper for you.