Where can I find spec sheet on the 034, 034 Super, 036/Pro. Can't find them on the STIHL site.
20" wood all the time, the MS290 would be only a budget contingency option for me. It is roughly equal to the 455 Rancher in power but I would expect far longer life from that engine however.
I'd be looking at a used 034, 034 Super, 036/Pro, MS360, MS361 if you were really in a hurry and on a budget.
For new saws, the 391 isn't overkill for 2-3 cords a year. Should run the hell outta a 20" bar in any hardwood too. It's going to be a whole 'nother world compared to that 455R too.
If you think you'd be cutting more than 2-3 cord in the future, as I see you have a couple stoves to feed, I'd just slide on up to the MS362 (a pro saw) and not worry about the saw for 20+ years. Saw loses over a lb in weight and picks up .2 hp over the 391 as well. I know it's a big chunk to bite off, especialy if you were looking at the $400 category, (DSRP on the MS362 20" is roughly $700) but nobody has ever regretted buying a professional grade saw for the kind of wood cutting a lot of us do around here.