Having problems with 360 engine

Have just got our 74 dart on the road this summer, maybe 60-75 miles on mostly a complete 360 rebuilt engine.

Went to a cruise night and found the engine was smoking and was losing oil pressure. A trip to the mechanic found the crane roller rockers bolts had broken off. Not all of them but several. No damage to the motor. Crane is good enough to replace the bolts, but are we going to have trouble with this every few 100 miles.

Anyone else experience problems like this, how to solve?