you can have the power turned up to 500/1850 in the ecm to go beyond that you have to dive into the engine, mine is a 485/1850 and pulls well..
as for the oil consumption it is not that bad for the miles you have, get the overhead done and turn the power up if you wish avg oil consumption is 1 gallon per 10,000 miles and that is just from the oil breaking down no big deal