I have a customer who wants me to machine him a set of connecting rods for a vtwin motor (it's a lawn mower engine). The stock rods are cast aluminum and he wants something stronger. There are some companies that make some aftermarket aluminum rods for motor similar to his but not for his particular motor. Has anyone made a set of rods before? I'm not sure what grade aluminum the stock rods are, Can I use 6061 or should I use 7075? Is there anything I should take into consideration before I start machining these..for instance, rod stretch, heat, etc...? The stock rods seem very cheap even for a 35hp motor.