Hi Brian
I'm not sure either that bow weight is a big deal - It's not as if you have to make a kill, so power is really only related to clearance in the event of overhanging foliage I think. On the two occasions I've shot a field round, I never had a problem with 36# modern carbon limbs, so with a trad bowI'd have to guess but I'd say 42#+ or an arrow speed of 200fps+ should be sufficient for most situations? I suppose it depends on how "trad" you want to go with materials (e.g. arrow and string materials?)