It is true that propane orifices are smaller. They are smaller, because propane requires more air in the air/flue mixture than natural gas. That is why it is very important to choose the right drill size when drilling out the orifice since there is not an adjustment for air flow. I prefer banjo...
Here is how we setup our stand:
https://www.homebrewtalk.com/f51/another-brew-stand-10-months-making-360447/
I prefer a manual controlled propane setup like this:
1) 0-30 gas regulator to manifold
2) manifold to ball valve (for on/off)
3) ball valve to needle valve (for gas flow control)
4)...
Propane is high pressure and natural gas is low pressure, so you will have to change a few things on your stand to make it work. You will need to replace the high pressure regulator to a low pressure regulator, the gas line between the regulator and flow control valves (needle valves) to larger...