Welcome aboard nice looking car.
Definitely La cylinder heads an rocker arm assembly. You could possibly remove the rocker arm assembly and look down through the head into the lifter Valley to determine if it has a roller cam. Another thing you might do is look on the side of the block and see what the date is. If it's an 89 90 or 91 there's a chance it's a roller motor.
Definitely looks like an 8 3/4 rearend.
