NEED ADVICE/ Recommendations on...Rear END ?

[summerj]

Hello All- Just purchased a '65 fleetside last weekend. I dont know much about the what appears to be the stock rear end in it. (The pumpkin is round like some of the other Eatons I have seen on here.

I have the opportunity to purchase a 1989 Chevy Iroc Posi rear end. ($100) Assuming its the same width, would this be an upgrade. I realize I may have to move the spring pearches but thats not a big deal to me. AM I Under ESTIMATING THis JOB? Yesterday I notice a small puddle of thick gear oil on the drive way from the current rear end.

Is this Eaton Rear End Worth Keeping? Or will the IROC Posi Be an upgrade?I will also be adding disk brakes to the front so I could find some 5 bolt rotors to match the IROC Posi Rear.

truck has a mid 70's 350 with power glide. I am looking to swap it for a 30 spline 700R4.

I am setting this truck up as a daily driver. It needs to have good brake on it as I will also be pulling a trailer.