I'd advise treating the NY target rifle and chunk gun as two different projects. There's traditions in chunk as well and fads and things that work. A puny 1 3/8" 44+" .50 will not be any sort of handicap in chunk, and you'll be better equipped than many (most?) at the York Shoot, which is approximately (my guess) 30% frequent/regular chunk shooters, while many more only shoot chunk matches once or twice a year. I've talked to several folks who only shoot at pall Mall... Depending on where you live and how much chunk you've shot, maybe just use what you've got for York and see if you like it and if there's a good number of chunk shoots you're likely to attend... Practice and experience are more important than the rifle, however, so if you like chunk and still want to build that type of rifle, I can't see any reason not to, and you'll have better ideas on details with a few chunk matches under your belt.