Hello Kevin .
To burn the carbon out of the intake on the carb type motor you will need to remover the carb and spark plugs . I think it is best to clean one passage at a time ( turn the motor by hand until the intake valve opens ) and not let the manifold get too hot. You can use some water on the outer part of the intake to tell when it is boiling and getting too hot.
Compressed air and nozzle will get you started on the top side of the intake . Also I used the connection hose from a compression tester to put air into each cylinder.
Once you burn most of the carbon out you can come back and add a little oxygen with your cutting torch . Be carfull !! the oxygen on burning carbon is like a small explsion.!!
When I cleaned the carbon from my 460 ford it took just about all day . When I clean it out of the trucks I have now it only a couple of min.
I’m glad you brought this subject up . It has been a few weeks that I have clean my intakes . Better to do it here on the farm vs happening down town
PS Keep in mind there is a lot of deference in a motor building up carbon vs a motor getting tared up .