I assume you're speaking of the hard lines. The flare nuts should be manipulated with a flare nut wrench. An open end plus a very educated and cautious elbow is alright when everything is fresh and clean, but when you're dealing with 45 year old rusty fittings, they're likely to round off as you've found out. Pre-treating with a quality penetrating oil such as kano kroil sometimes helps in the freeing process. There is no pre-bent hard line kit for the IH full-size trucks. IHPA offers a kit for the sii's, but the dimensions are too short and narrow to work in a full-size. If you can get your originals out without destroying them too badly, you might have some luck with a local brake shop making you some replacements using the old ones as a pattern.