I'll avoid any of my sarcastic levity and try to, indeed, be helpful.
Firstly, N Scale's relationship to HO Scale is a precise 6:11.0236 ratio; you can round that off to a 6:11 ratio and be less than a quarter of one percent too small. Take 18 inches divide by 11 and multiply by 6 and you will come up with 9.82 (9 13/16) inches; that HO Scale 22 inch radius curve scales
down to 12 inches in N Scale. With these figures in mind I think you can probably see why N Scalers very frequently utilize HO Scale (track) measurements for their layouts. An N Scale 18 inch radius curve scales
up to a 33 inch HO Scale curve; a 22 inch radius curve scales up proportionately. An N Scale 4 by measures to an HO Scale 7 1/3 by 14 2/3 feet . . . . . . . . . . and you don't need any access hatches!!!
Unfortunately Mike, you will find that the modeling era you outline in your post is going to be an extremely difficult one to model in N Scale. The predominant locomotive of that era was the American Standard 4-4-0 followed in popularity by the Mogul 2-6-0 and the Ten-Wheeler 4-6-0. There were some Decapod 2-10-0s around and the Consolidation 2-8-0 was growing in popularity and would, by the turn of the Century, become the dominant locomotive on American rails. There were no Mikado 2-8-2s nor Pacific 4-6-2s nor any other
large steam locomotives gracing the rails.
Model Power has the American Standard 4-4-0 and the Mogul 2-6-0 available but I can offer no testimony as to how these might run. The MDC/Athearn Consolidation 2-8-0 has lines appropriate for the 1880s era; when this locomotive first became available as a Roundhouse product it did not get enthusiastic reviews, however Athearn has apparently improved it and more recent reviews give it higher ratings. The Decapod and Ten-Wheeler pose a problem because none are, or have ever been, offered; you should keep in mind, however, that only the Pennsylvania Railroad fielded a sizable fleet of the Decapod wheel arrangement and they were virtual giants - what did they call them? Hippos? - compared to the size you would have encountered in the 1880s. The Ten-Wheeler was quite ubiquitous and it is therefore surprising that N Scale manufacturers have virtually ignored that wheel arrangement.
Depending upon your skill level you could probably 'bash' a Decapod or Ten-Wheeler using a number of available chassis/boilers as a base; keep in mind that such a 'bash' would require both frame and superstructure modification.
Assuming that you can accept 4-4-0s, 2-6-0s, and 2-8-0s as motive power your main predicament is going come in freight car rolling stock; there just ain't none! A few years back Roundhouse offered 'old time' freight cars that were
similiar to cars of that era and could be made to work. Bachmann also had rolling stock from that era but they disappeared years ago.
Things are a little rosier in the passenger car field, however, they may be just a little hard to lay your hands on. MDC/Roundhouse put out the 34 foot 'shorties' and the scale specific hobby mags have had articles on lengthening these; MDC/Roundhouse also offered 50 foot cars in the same general configuration which modelers have also
stretched into longer units. MDC/Roundhouse at one time offered 80 foot Pullman Palace cars which were, pure and simple, drop-dead-gorgeous. Unfortunately - I sure am tired of that word but have yet to figure out how to avoid using it; maybe I should start saying
infelicitously or
unhappily - anyway, as luck would have it, to the best of my knowledge none of these are currently available.
Let me add one thing in regards to Passenger cars.
N Scale Railroading Magazine began a series in their Sept-Oct '07 issue by Paul J. Downs titled
Easy Car Sides for Modernized Heavyweights; I can't see why, if a car can be modernized, it could not be backdated with wood-sheathing to create a car appropriate to the 1880s era which you have indicated you would like to model.
Hope I have been of some assistance with my response.