An over statement, although they have been problematic. I've done 5 of em so far, only 2 of the 5 carbs work, and only after I modified the choke so it does not stick. Also, the chain adjusters all need some work or replacement parts, and I always use an OEM piston pin bearing. I also put a washer to block the impulse from going on too far, and another washer under the high left vibration mount to reduce vibes. If you use a OEM carb you also usually have to modify the control lever to get the choke to work. One brake flag was bad, and the others need the hole enlarged on the case side.
I replace the recoil handle and cord with OEM Elastostart, and lube the recoils with Fluid Film, but they have all worked fine for me.
A Tree Guy wanted one of the Big Bore kits I did, he uses it daily, and it has not come back yet.
I've got another Big Bore jug with an OEM piston, and a Hybrid with HL Supply jug and OEM piston, and one that just has a used OEM 044 P+C.
The 5th one got the 044 crank and was used as the basis for my Dr Al Hybrid.
They are a PITA, but now that I know what to do with them, I'm looking forward to building more of them. The case, cranks, main bearings (if you flush them), flywheel, coil and tank holder (other than the control lever) have all functioned fine as far as I know. Plus, none of my kits had missing parts. Not an easy build, but you get a lot for your money. I'm also still using all the clutches, drums and bearings that came with them.
Time will tell how everything holds up.
I guess you just have to really like 440s or hybrids to do one, or have an OEM saw in need of lots of parts. OME parts can get expensive fast.