No
Yes it will, as long as it is the same gauge and shell length. I just tried it with two shotguns on the rack.
No
No.
no the 1300 barrel does not have gas ports in it yes the 1300 barrel will fit ,no it does not have the gas ports BUT any competent machine shop or gunsmith can drill out the ports for you.
Try a 1300 barrel
No
no
No
The only barrels that will fit the Winchester model 120 are all model 1300 winchester barrels,and most model1200 Winchester barrels.So the answer to your question is No.
Any barrel will fit only if you replace the tube also to a conventional 1300 tube.
I recently called the Winchester historian and he said they were the same gun also a model 1200 barrel will fit.