Steve - I just rebuilt an 034 for a friend on Sunday using an Episan piston from Dandikrop on eBay - cost me barely under $50 CDN shipping included, and was here in about a week and a half. I was quite impressed with it - I compared it side-by-side to the scored OEM piston and it was all but identical in every way. It did have some slightly rougher casting lines in the windows & around the pin bosses, but a minute with the Dremel cleaned that up nicely. I did open the windows up a little bit while I was at it, but not a whole lot since it wasn't my saw. I stuck with the OEM pin & circlips, all of which fit up perfectly. My only (small) complaint is that the listing has photos of a Meteor piston & box, though the fine print doesn't guarantee that. I have no problems with what I received though.
For the money vs. OEM, I'm quite happy with the quality and performance of it. After a tank and a half, it's blowing 160 PSI @ 3000' elevation. I set the squish at a little wider .026 for a bit of added safety. At first it was wanting to idle low or stall if tipped forward with the bar pointed straight at the ground, but that seems to have worked out now. I'd never cut with an 034 before, but I took this one out today to run another tank through it for break-in and was really happy with its performance. I was cutting ~8-10" Douglas Fir and it felt every bit as fast as my 371 in smaller wood like that. I also buried the 20" bar in more D. Fir both in rip cuts and crosscuts and it pulled that very well too. FWIW it's wearing 3/8 semi-skip chain.