I have a Thunderhead that I air layered off the rootstock (a 3-year long project in my climate) but have not bothered with any of the other 'miniature/dwarf' varieties simply because it is so easy to reduce needle size on standard JBP. The problem with most nursery stock is that the trunk is arrow-straight but doesn't taper --> it just isn't close to ever being a formal upright.
I suggest that you get some young JBP (from
@cmeg1,
@kingsville grower, or kaedabonsai-en, say) or even just get some good seed. They grow fast and you will have the liberty to create whatever trunk and size of bonsai you might like (there is a 6-year contest in progress on BNut now and a post about pines '6 years later' by Eric Schrader --> search
Of course, it does not have to be an either-or proposition. You could do both. With JWP one pretty much must accept it being grafted. You'll have a similar challenge to figure out how to hide the union. If it is grafted high, one can simply lower a branch and obscure it with foliage. If it is grafted low, one can forgo displaying nebari and fake it with mounded soil/rocks (commonly the case with cork bark varieties). If it is grafted somewhere in between, it won't be noticed if the root stock heads toward the back, say, but otherwise you'll be screwed. If there aren't any wiggles to the trunk near the union you won't be able to make it happen with the nursery stock you're looking at; it will simply be too rigid. IOW, make your pick with this in mind.