I know you may not want to hear this but if I were in your situation Id go with an LQ4 shortblock and throw your 799s on there with a 216/220 cam, nice compression, and very torquey. Im running an LQ4 in my heavy pig ECSB Z71 with a gt2-3 and its very nice and torquey, you could benefit even more with your big tires. I plan on getting a set of 243/799 heads to throw on mine when I have to tear it down to swap lifters(damn lifter tick). You will see a nice kick in the pants and Id bet even a gain in mileage even though youre going with a bigger engine. 5.3s in heavy trucks with big tires just dont work well no matter how you try and crutch it along.

 

Believe me I wish I could, but I can't. Maybe one of these days. What do you think about the set up I listed. I that cam to big to small for those heads???

 

I dont think you will see much gain since the chambers are almost the same size as stock heads.

 

What about the springs, Everything I search I still come up with the 799 heads having the ls6 springs????? Come on guys, the heads have to be worth some improvement in power of I'm milling them, bringing compression up a half a point to 10:1 and the 799's flow better. Combined with the cam won't the heads help at least 15 hp.

 

Considering the stage 2.5 PRC 5.3s that flow way better than the 243s are only worth about 30rwhp on a LQ4 Id put money on maybe 10hp with them mild on a 5.3. Theyre just not that great of a choice for a 5.3. The cam is pretty good but it would need a bigger converter, hell a stock cam in a stock tire sized truck needs a 3000 converter to really shine. My 2400 with the baby cam LQ4 with 32s really needs more converter but Ive got a radix sitting on the shelf to cure that here shortly. As far as springs go I really dont know, Ive always seen everyone on here replace them when they do a cam swap. Doesnt mean theyre not LS6 springs but theyre definitely not yellow. The only way to know for sure is to test them.

 

If I were to go ahead and put these on after milling them .030 would I still be able to use them on a 6.0 later on?? Where is the cheapest place to get oem bolts and head gaskets and do I need to new manifold to heads and manifold to block gaskets??

 

You gunna do sumthin about that soon?

 

I got my bolts and fel pro gaskets from summit for 70 bucks total I think, been a while now. You could still use them on a 6.0 but it would need to be an LQ4, an LQ9 would net too high of a CR for your heavy truck.
Not going to lie probably not, if I had to put money on it Id say maybe April.

 

Same boat with the cam, my A/C went out day before yesterday. Yay me

 

fwiw ... I'm looking at putting a set of 243's milled .030 with a .030 head gasket, and we've calculated my compression out to be about 10.15, without the thinner head gasket, your 5.3 is looking at a very small boost in compression, maybe put you somewhere like 9.75 if you use stock thickness head gasket. You're going to go from 61.1cc Chambers on your stock heads, to 59cc combustion chambers on your 799s if you mill them .030