Check on Amazon. I'm a buyer at my company and just purchased these for a little IT project. 11 bucks for 1,000 various transistors. You should be able to find what you need there, but how good the quality is will not be known. All China stuff these days.
Or there is an igniter for an '83 VT500 on eBay for about $48 shipped: https://www.[ebay].com/itm/334290106376
It would have to be an 85 or 86 box. Unfortunatly, they are few and pricey. The pre 85s used a seperate igniter box for each cylinder.
I may just order the transistors from China and hope for the best.
Two alternate part numbers mentioned: MJE5742G or BU941.
MJE5742G doesn't have a zener diode, so you'd need to install that separately.
Also, on a Gixxer forum one guy just replaced the capacitors & cleaned up or resoldered some of the connections and removed some of the melted gunk which can be conductive. And that guy or another gixxer guy replaced some of the resistors w brass rod. If interested, I saved the links.