Put a rebuilt 292 y-block in my Ford F100.  Turned fine by hand and started and ran OK, but rather high on idle.  So decided to change the carb.  Then had a hard time starting it and when it did start a loud clunking/clanking noise coming from top front of engine. Shut it off immediately hoping not to damage it ... sounded damaged.  Am not a mechanic and in small town not many familiar with Y-Blocks so need help determining what to go through to determine whats wrong.  Need sequence of checks to go through without using the starter or turning it over with the starter. Seem to be taking more steps backward than forward with this truck.  So any help is appreciated