Have a word with
Fowlers who list the seals at £11.32 each. or
Yambits who show them in copper (£2.99) or fibre (£1.80).
One other point, you say that your frame is a 2EN; this is an '87 - '90 frame for the European market which was without V-Boost with km/h Tacho and light switch, 35mm-Carburettor, max revs 8500 rpm.
I also have it at the back of my mind (but can't find any reference) that they had smaller exhaust ports.
I say this as I was gives some of the gaskets but they were smaller than those in my bike (a '99 US model).
I'll have a look to see if I still have them and if they are the size you want you are welcome to have them.
Watch this space.....well not
this space because it is already occupied.
I guess watch another space would be better?