Turns out, I was able to make myself a forge sooner than I thought using scrap at work. It's looking good, and just needs refractory material to finish it off.
Only problem is that it was a kind of spur-of-the-moment piece of fabrication, and I misremembered the inlet pipe for the burner's size, and welded on a 1.5" OD tube (1.25" ID). The plan I had in mind called for a 2.5" inlet pipe-While I could grind the pipe off and replace it with a 2.5" pipe, it looks nice how it is, and the inside is laser cut so there aren't any rough edges to interfere with the flame.
So I'm wondering if amongst the many burner designs floating around, there is one that will slide into the pipe I've got. The only modifications I made to the plan linked to about were to make the main body out of rolled and welded 14ga CRS, and to weld a back on the main body with a 4" dia passthrough with a flip-up door.
If I have to, I'll suck it up and grind the pipe off. I just hate to mess up an otherwise nice fabrication job with a grinder if I don't have to.
In another sort-of related question- does anyone here run an oxygen/acetaline burner on their forge? I guess the two questions I'd have about it were whether the CO or other dangerous gas emissions were reduced in doing this, and whether it makes for a hotter forge with a smaller burner or lower gas consumption. It might be a good fit for me, as it could serve dual-purpose as a welder/cutting torch also.