So... ^Bob has most of it covered and your other replies here.
Good stuff.
Tap out your HD stock filters ever tank or two and do run the felt wrap covers when your milling.
I run 084s, mostly stock with a muffler mod for now while the next cylinder is being worked out on porting. They will get many more mods by this fall like Vstacks and better oil foam filters. It's only cut 0.025 and 0.038 with a flattop piston in it. I'm sticking with pump gas under 200 psi so I won't be cooking or pounding out the bearings in short order. Staying under 200psi is prudent on a really long bar. Cut out every other set of chain cutters and touch it up square if you need to go faster or lighten the load on it.
Nobody ever mentions this but go over ever single screw, bolt, clip and the decomp button including the case screws so you know it's all tight and right. Avoiding a burn-down is paramount. If it does something funny just stop and get after it pronto!
My 660 ported pulls a 60" Cannon but struggles in hardwood over 42" wide with full comp full chisel on the four foot alaskan. It's base and quench (squish) cut and the quench is 0.025, 7 degrees added timing lead (needs less really), no popup, about 190psi compression, pia muffler piped but getting changed again, K&N with Outerwears, Vstack and ported carb inlet with choke work, on pump 89 but she pops on 86 due to hot spots. It's a monster on roids just for milling with some parts deleted permanently. It usually runs a 36" or a 40" roller nose on the three foot mill. Mason Husky something screen name and he ran it in big oak up in PA this spring bucking at Dewayne's killer spot
Your 880 can handle a gasket delete or a small base cut. Just remember you limit the transfer duration if you just drop it down. Some people will tell you my quench is too tight like Donny Walker but he builds everyday commercial work saws to not be ridiculously high compression and leaves plenty of room for carbon to build up and never have an issue. I'm on a self cleaning train and run my smaller stuff like 361's or 2s near 0.014 quench. Each to his own. I go for grunt not more RPMs.
Most of the saws here are tuned between 12K to 13k milling or not from 200Ts right through to the big dogs. I don't recommend you tune it above 11.5 on your big saw. Stay on the safe side and tune yours a bit fat. Gas cools pistons. Just get your exhaust fumes heading in the right direction which is not at the mill.
Quality synthetic mix oil at 40-1 or more of you can burn it. I find good synthetic oil @32-1 bleeds out my mufflers and does hurt power just a touch. You can run 25-1 if you like with lesser offerings. Each to his or her own. Nothing else to tell but to keep it CLEAN inside and out. That includes daily grease on the drum bearing and clean out the oil pump area every so often.
Hope that helps some.