What could cause this? 360 problems ####update####

here is what i have. 1978 360 E58, stock dished pistons, 587 heads, sealed power 214/224 duration, 443/465 lift. I put engine on my run stand and it wouldnt start or even fire. No compression. Pulled the heads off and the number one exhaust valve was broken. Every exhaust valve hit the piston. The heads were surfaced and i used the thin mr gasket head gaskets. Stock push rods and rockers. Any ideas? This is a pic of the number one piston

1DE95C4B-F8C1-4025-B242-057090E8B182.jpeg