i can buy a set of precision 65#s right now for a nice price... is there really any difference in the injector besides the EV1 style clip and the length...

 

Assuming you're using an L92 style intake/fuel rail/shorty injectors, the fuel rail likely won't fit without some longer stanchions. I wouldn't know if there are any other clearance issues around the rail of manifold.

You already know about the EV1 to EV6 connectors, and LS1 injectors were rated for 43.5 PSI fuel pressure, so running them on a 58 PSI system will increase their flow rate.

I have no idea if the spray pattern would be any different, but if you look at an LS1 injector side by side to a later generation one, the newer ones have more of a nozzle (longer distance between the end of the injector and the base o-ring).