rndball,
Welcome to the Muzzleloading forum!
It has been my privilege to handle a few originals. Not a lot, but several. Of these, some had hand-hammered barrels. All were percussion. All of the hand forged barrels I have seen were swamped except one. This one was tapered, and considerably shorter than the others, and the rifle showed evidence of having been shortened. I believe the barrel had originally been swamped, but was cut off at the waist (the narrowest part of a swamped barrel), resulting in a taper.
The thing to consider is whether you want a "poor boy" to save yourself some money, or if you just like the style. A swamped barrel would be perfectly acceptable on a plain rifle if you can afford it, and it will improve the balance and "agility" of your rifle. I think very early rifles would have very likely had swamped barrels. Later rifles could have used commercially produced parallel-sided barrel blanks, although I understand these were often smooth-bored when obtained, and were hand-rifled by the gun builder. I think hand-hammered barrels may have held on longest in the more remote areas, well into the percussion era.
I would also like to say that all of these rifles except that one, which had undoubtedly been cut off, had long barrels, averaging around 42"-44". These short-barreled "SMR's" that we are seeing nowadays are a modern phenomenon, although I suppose one could rationalize and say the shorter barrels represent cut-offs.
Most of us think of "poor boy" rifles as a "southern thing," but I believe they may have been more universal, and we know very simple rifles also came out of the Pennsylvania shops. We know these as schimmels. Chuck Dixon wrote a really nice article on them, and Gary Ludwig was kind enough to send me a copy of it. Mr. Dixon suggested that in at least some cases, gunsmiths would build very simple rifles "on spec" and leave them unfinished. A customer could pick one out and specify what degree of finish, furniture, and ornamentation would be added on. The basic components of the unfinished rifles (lock, stock, and barrel) would be the same as on the more expensive guns. The customer might elect to leave the rifle in its most basic form, to save money (and/or time), or specify adding on a butt plate, patchbox, nosecap, decorative inlays and carving, etc.
I did read a fairly lively discussion recently, I think on this forum, regarding brass versus iron mountings, whether forged iron was really cheaper, back in the day, and used to save money, or if it was purely stylistic. I didn't participate in that... I would have had to speculate. I will say that if you want a southern-styled "poor boy," iron might be more appropriate, and I would like to add that not all iron-mounted southern rifles were "poor boys." A Pennsylvania schimmel would more likely have its sparse furniture made of brass. There are also some rifles out there with mixed iron and brass furniture, and a few southern rifles with no buttplate but a heelplate of bone to protect that vulnerable part of the stock.
Regarding wood, I believe a northern schimmel would have most likely been stocked in maple. Of the half-dozen or so southern rifles I have actually handled, stock woods ran about 50/50 black walnut versus "white" wood, definitely curly maple in two cases (both Tennessee rifles) but possibly beech or applewood on a real, classic "poor boy" from the backwoods of Kentucky.
So, if you want a "poor boy" because you like the style, I think that's great! I don't currently own one, but I love 'em. If I were building one or having one built, I would decide on a regional style and use best-quality components (lock, barrel, and triggers) to ensure having a reliable, accurate rifle that will be fun to shoot. I would use a full-length barrel of 42" to 44" and might very well order it swamped. If I wanted a curly maple stock with a little figure, I would not hesitate to use it.
You may want to browse through the posts on the ALR forum to see some pictures of originals.
Best regards,
Notchy Bob