Thanks for sharing your experience and tips
What did use your oxyacetylene torch for? Whenever I used one, I found it was too powerful and hot for any small work, same with electric arc solder
On the other hand, I had very good feedback with propane-mixes handheld torches, which are something closer to what you've described.
Fire bricks are expensive and AFAIK the best ones are made out of alumina, which is outstanding yet brittle.
I don't want to go too much offtopic, but I think alumina could be bought raw then compressed into bricks, though I've never tried.