Have the big end of the rods checked for size and roundness before you sign up to having them resized. Stock slant rods are pretty tough and those engines when new were low power, they could easily be fine the way they are. Any good machine shop can check them for you. And unless you are building the slant for big power and high RPM, or the rods have been torqued and then taken apart numerous times. the stock OE rod bolts will be fine.