What is the hp goal of the 273? IMO you'd be just fine with the stock caps and some good bolts or studs if its just going to be around 400hp like your sig suggests
x2 If you're really serious, Stud the bottom end. And if you're going nuts use a main cap girdle. You're not going to blow up your main caps, period. You're going to break a rod, walk the caps, break main bolts, or even crack your block long before your main caps come apart. That's assuming there isn't a defect in them. Which, Sadly, I'd be more worried about in the magnum parts than the older ones.
Edit: If you're turning 7.5k, use a damn good rotating assembly, balance it as tight as anybody near you can, and put all ARP bolts/studs in it.
