The 45-70 is a awsome gun in any configuration you have..short barrels are fun to tote around..long barrels give you a long siting plane to work with for open sites.Me personally..I prefere the feel and balance of the longer barrels..this goes a long way for shooting off hand..which is something I enjoy doing with them..When I get a 32" Buff barrel..it will be cut back though..probably to 26" or 28"..I will do this because I don't shoot black powder..and with todays modern powders that long of a barrel isn't really needed...It is more historically correct and needed if your planning on doing any period type shooting sports..but..for just hunting or target work it's not.The performance level levels off after the 28" mark with modern powders.The short barrels give almost as much..so it really comes down to personal preference..which is why most 45-70 owners usually want more than just 1 of them...
I've owned several Marlins with barrels ranging from 18-1/2" to 26"..and a nice Limited 22" Ultra..they all are capable of great accuracy and give spectacular results on game....Your nickled reciever will look good with any barrel lenght you choose...be it shorter than 22" or not....but if you elect to go with the full 32" barrel and want to shoot open sites..I highly recommend getting the Buff Classic stock to keep it original when you do..the stock dimensions will aid you in using the open sites...as too getting some of the laminated ones if you prefere without the Monte Carlo design....Quickdtoo and others have changed the curved metal butt plate and have added real nice recoil pads to tame the recoil down quite a bit and make it more enjoyable to shoot..and is something you might want to consider doing as well..Now..if you want to make a super hunting rifle and have it scoped...the regular 22" barrels are really nice as well..this was my Limited witha nice green laminated checkered stock set put on it..and a Limbsaver recoil pad added..I also added 2lbs of weight to the stock to aid in recoil reduction of my 300 grain Nosler loads..

Any way you elect to go will give you a super gun that you will enjoy for years to come..and a good start to you 45-70 collection which will surely follow..
Mac