I wouldn't use a circular saw with a metal blade if I had any other means. They have plastic parts on the saw guard that can melt and spins much faster than a chop saw or multi-saw (a circular saw that's made for metal, aka dry saw. Like a cold saw just higher RPM). I'll cut aluminum all day long with a circular saw but never steel. Not to say I've never seen a guy at a construction site cut plate with a table saw. Rebar with a circular saw, or pipe with a mitre saw (or any combination)...I have. You gotta decide, when working with metal, it's a good idea to know the tool you use cause they can all hurt you. I personally owned a metal fab shop for years and have seen a bubbling idiot hurt himself with an orbital sander and a skilled artist carve thick steel plate with an angle grinder like it was a paint brush. The trick is to understand how the tool your gonna use works, how it can fail, and prepare accordingly. The angle grinder, for example, is known for catching, bucking, and then blowing a disc up in your hand/face/etc. If you know it can happen, prepare for it (correct protective gear), and cut at the right speed, you could be safe and successful. Get too aggressive, forget glasses, and fail to brace your support hand, you could change your BB name to OneEye. The real answer to your question depends on what you have access to, what you're comfortable using, and how long you want it to take. I'd make that cut with a plasma, a cut-off wheel, or a torch (in that order) in my shop. I always tend to pick the method that requires the least amount of cleanup. If your trying to do it on the cheap, angle grinder. Justify a cool-tool purchase to the Mrs, a $2k plasma should do the trick.