Coughing 360

Have a '77 360..80k in a sportsman B series van camper.. Just replaced the right bank exhaust gasket.. noticed lots of anti freeze coming from the last rear bolt hole on head when I removed it..is this normal? Secondly..this old beast ran great before I changed this gasket. It still starts fine..but coughs under load now. I completely warmed it up before hitting the road. Here is my list..check gas line, accelerator pump diaphragm, vacuum leak, firing order and timing... Wonder how to test fuel pump. Other than that..dash lights quit..cab overhead light quit. Love the old school stuff..my 16 year old son is diggin it too..