I got my .22 Pro/elite for £220 from Youngmans when they went out of production.
My P/e's have both been worked on by Steve pope at v-Mach and did not require the breech shim conversion, that my Hw80 and 98 had done. It was not needed on the P/e due to being a great set up .
The breech shims on the hw guns have room for improvement so Steve recommend,s is bigger shims.
I can't comment on the Diana breech.
Les..