I am not a HPOF "judge" but I do own a couple of HPOF cars so I have been where you are. On all my HPOF cars, my hoses, belts, tires and muffler have been replaced (with period correct items) and I got HPOF without an issue. I haven't taken them through a second round for Original HPOF but I think the main difference is that you aren't allowed as many deductions the second time around. From my limited knowledge, your running boards would be a deduction (possibly 1 point each) and radio another deduction. I may be wrong but I think items that are maintenance/safety items (tires, hoses, belts) are considered ok. I don't think running on 25 plus year old tires, hoses or belts is safe.
Bob