I had a 273 4bbl and it loved to rev! I never had rod problems, or bearings either. If you get the rods re-sized and checked they should be good to go. I have seen the 2bbl motors snap a rod, over revved the thing I was told. If I was going to put it together I'd use the new sir rods. Build a rock solid bottom end. Maybe try to find light pistons to make up the weight difference. At least use the strongest rod bolts you can on the old rods. I'd hate to tear a new motor apart for a $120.00.