I would
not recommend an overhead gas radiant heater.
This is what I've been running in my 1200 sq/ft cement shop for a dozen years and it's not a pleasant feeling heat.
Something about a hot head & cold feet, together with $230xx gas bills, just about has me ready to tear it off the ceiling!
Also, dust builds up on top radiant units ...which burns, stinks & makes headaches.
I think my next choice would be a unit heater hanging in one corner. I'd still use gas, but I think the fan directing the heat in a nice big circle would warm
everything evenly
...and make good use of less heat.
Less heat = less $$ =