TKR88GTA

ok so like the title says is it possible to check the crankshaft while its still in the car. im trying to help my brother find out whats wrong with his 98 h/c/i LS1 camaro. he started with a loud knock after he blew a tire on the highway and spun out into the median thats full of mesquites. he noticed the sway bar had pushed up against the crank shaft pulley. he unbent it and after that the loud knock went away and now its just a pretty loud tapping noise. i took off the valve covers one of his rockers needs to be replaced and one of the rocker arms was just sitting there you could move it up and down with out much effort. im guessing thats a stuck lifter since the pushrod isnt bent. so obviously thats counting for some of the noise we are hearing. before i tear down into this motor i want to see if the crank shaft could be eliminated from the current problems and if we can just get away with a top end fix.

any info much appreciated!