It's possible one of the racing specialty places like ARP might have something suitable. Instead of cap screws, studs might be a better choice. When we wanted to build a really bulletproof lower end on the race engines, we would install Grade 8 studs in the block and use hardened steel grade 8 washers and nuts to secure the main caps.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!