Can build a stroker, but cheap out on good fasteners?? Hmmn.

 

AT least get a New set of Chevrolet fasteners. Then do a search at to the orientation of the main cap location AND direction. Then before tightening the caps give the cap a good whack with a dead blow hammer or rubber mallet, to seat the cap before the first round of the torque wrench. I don't have anything else to offer. But toss out those old bolts.

 

My guess is that you're going past 15 ft lbs on the initial tq setting and then when you angle torque them they break cause they've gone way too far.

What kind of tq wrench are you using? On my click style tq wrench 15 ft lbs is super hard to feel and I've gone past my tq spec a few times at lower tq levels. So now when I have to do under 30 or so ft lbs tq I take the tq wrench to the vise and do a few practice pulls to feel for that low tq click, which it doesn't make a click sound set that low, so I have to watch the wrench pivot at that point that it pivots when it does make the click sound. Hope that makes sense.

 

It must be a torquing issue. For the bolts to continue to snap, the only thing I can think of is they are being over torqued.
What brand of bolts are you using, what torque wrench/angle gauge?
Without the caps in place, do the bolts freely spin and bottom out in the bolt holes?
I would lie/cheat/steal/kill/rent my girlfriend/wife out for the day, to find a way to get some cash and just get the $220 ARP Studs. To built a nice engine like that, you should use quality fasteners, but that is my opinion.

Also, is it just me, or does it look like the coating is worn off on the main bearings?