Ok, I'm getting ready to replace the cracked Castech 706 heads on my 2000 GMC Sierra 4.8 with a set of reconditioned non-Castech 862 castings running Chevrolet Performance 12499224 springs. While doing so I'm going to change the cam/lifter and probably timing chain. I'm looking to run either the Comp Cams XR259HR or XR265HR cam. My question is I've been told I should shave a little off the heads for starters. How much?? Also which cam would you recommend for good performance but will pull my 18' bass boat often? Initially I will be running the stock exhaust manifolds but plan on putting long tubes and a full mandrel bent dual exhaust on it not long after. I also will be running the stock converter initially but an not against going to a slight higher stall if it's recommended. The trans I had rebuilt a few years ago and it currently has a corvette servo in it so it's got a real snappy 1-2 shift. It also has a 3.73 gear with an Auburn limited slip unit. Stock size 15" tires.
Is a new oil pump recommended or will my stock one be fine? I was told I should replace the pickup O-ring though. TIA

 

https://www.performancetrucks.net/fo...-heads-434041/

There's a little math formula in this thread that can help with your milling question.

As for the cam..
I would be very careful with taking other peoples advice on cam selection. I have always paid for my cam advice, and this method has treated me well.

I have always used Ed Curtis with FlowTechInduction to design a custom cam for the engines I build. They've performed exactly as I wanted them to.

There are plenty of sponsors here that would be glad to actually listen to your goals and either design a cam for you, or know which of their shelf cams would suite those goals best. I'd spend a few bucks extra and get with one of them.

 

in a 4.8 its tough to slap in a cam thats goign to do any better off the bottom than the stock cam. If pulling the boat is priority 1 im not sure I would be looking at cam swaps first. Boost will get the job done better.

If youre dead set on a cam those comp cams will be OK, but the smaller motor will want a tighter LSA to help boost low-mid torque.

 

https://www.performancetrucks.net/fo...prings-542965/

Just saying...

 

This is my daily driver and I just don't have the budget or time to get into boosting it or changing out the entire motor to a 5.3. Just looking to get the most power out of my 4.8 since I have to change the heads anyways.