Arp Head Bolts

I Just Built A .030 340 With Trw L2322f Pistons. Squared The Block, & Surfaced The Heads. I Used Arp Head Bolts That Were Tighten To Their Specs In Three Steps. The Engine Has 20 Passes On It. Blew A Head Gasket To The Outside On The Lower Portion. The Combustion Sealing Ring Was Still Intact. Some Of The Lower Row Bolts Wern't Very Tight. Has Anybody Had These Bolts Stretch Before. I Have The Same Set-up On My 360 With Eldo Heads, With 300+ Passes. No Concerns. I Am Putting The Same Fel Pro Gasket Back On, This Time I Will Retourque Them After It Has Heat Cycled. Whats Everyones Take On This.