I suspect that the torch body is the same and the tips that come with it are for natural gas…just having converted my natural gas grill to propane, I can tell you that the orifices for natural gas are a lot bigger, because the pressure of natural gas is so low compared to propane…so if there were any difference in the torch itself, it would be in the internal valves and the amount you would crack the valve open would be less for the propane, this making it more sensitive to how much you turn it. You can probably use the smaller natural gas tips for propane, they will just produce a much larger flame. The bigger ones, you’ll just have to see. You may need some smaller ones for the smallest flames with propane, but you are going to want the kit with the hypodermic needle tips in it anyway and the largest of these overlap in size with the smaller brass tips, so just order that kit and see if it and the nat. gas tips will give you enough of a graduated set. Another thought I have is that you could tap the top of the brass tips with a hammer and mushroom the hole down to a smaller size. There was recently some discussion here in response to my query about the hose to use, so you can look at that.
As far as the oxygen regulator, when you consider the cost of a good one plus what the oxygen tank is going to cost you, in the long term, a 5 lpm oxygen concentrator may be a better deal. They run anywhere from $150 to $350, depending on whether they have been reconditioned or just sold by some private individual. Possibly more than a tank and regulator, but then you won’t ever have to refill the tank or service the regulator and the concentrator is a safer setup. Just sayin’…-royjohn