Can I use a 4-pole breaker in place of a Gould 200 amp main breaker?
Never, never, never mix random brand-name breakers with random-brand-name panels.  Most of the 1" wide breakers will seem to physically fit, but they won't mate properly with the buses, and will arc and burn up.  This is a death sentence for the panel, so now you're into the ~$2000 of having one replaced whole.  

I get when you're dealing with an obsolete panel like ITE/Gould, Cutler Hammer, Challenger, Westinghouse, Murray, BRyant, etc. -- you go "gosh, this thing is totally unsupported, I have no choice but to root around eBay for used breakers". 

Not at all.  Most old brands - and every one I listed - have been acquired and merged, and are now new-brand panels readily available at electrical supply houses.  Those six I listed are now Siemens, Eaton, Eaton, Eaton, Siemens and Eaton. 

So I would call around to electrical supply houses (NOT big box stores) and find one who is a Siemens dealer.  Then come in with a photo of your panel label and of your old main breaker, especially any numbers it may have.  It is quite possible they can hand you a new-manufacture Siemens breaker that will fit.  They can also sell you THE correct branch circuit breakers for the panel.  Those can be worth modernizing, because  you can add AFCI or AFCI+GFCI functionality.