I Have a situation

Wait a minute, so the exhaust manifold has the small 273 port size and the head is a 360 port size. So the exhaust stream is hitting a 90 deg step as it enters the exh manifold. There you go. 273-318 Small-port cylinder heads, with the port diameter 1.09w x 1.55h, 360 has 1.30X1.70. That is a LARGE right angle speed bump.