Jets cost about £2.75 each or cheaper if you buy a box set.
I have a set but haven't used them yet as standard seems fine so far.
BTW the 34mm carb is quite a bit physicaly larger than a 32mm carb. I bought a 32mm for just £15 as I thought it might be useful for this or another project.
Note: You only need to change the pilot jet if the screw is not around one and a half turns. Not telling you how to suck eggs.