yea most likely it was the oil pump, i changed mine to a type r oil pump and my ls/vtec ran great, revved it to 8000 whenever i felt like it without a single problem, i also had arp rod bolts, but other then that i had a stock block. ls rods wont handle high rpm's but it shouldnt affect it if you revved it to 7500.

the only thing you can do is rebuild the bottom end, check your crank, if not get a new one and put a gsr oil pump on it

might as well do rods and pistons. and all the bearings