1987 R30/5.7 TBI Exhaust valve cam lobe on #7 cylinder worn off. Going to replace cam/lifters. My GM Service manual says to "Remove front engine mount bolts and raise engine"-but it does not say how high. Can't go very high or the rear of the engine will hit the firewall. Has anyone out there done a cam change on a '81-'87 with engine in truck? I realize I have to remove the A/C condenser, radiator and grill.