If that is the boiler I think it is.......it must be pretty old by now, about 40 years old I should think.
I would think that the sort of bits you need for it are pretty much unobtainable by now.
However there are lots of companys on the internet who supply sheet materials to make gaskets with. They are aimed mainly at the automotive industry but are perfect for what you need.
Making up gaskets and flanges for boilers is an easy job, I've done it myself on several occasions.
Best of Luck, Jon.
jondeau
January 2011