408 swap in my 65, some top end questions

[Jasons65]

Hi all, I was going to put a bone stock 6.0 lq4 in my truck but the motor I got looks like it has one cylinder producing much less compression than the others and has 180k miles on it. Rather than spend the extra money to rebuild it I already have a 408 lq4 with fully forged internals at my machine shop I was building for my nova. This motor was going to get ls3 heads but if I put it in my truck I would need to keep a truck intake to reuse my truck accessories so I figured I could have my lq4 heads ported and polished, put a daily driver cam in it and run the fast lsxrt intake so I'm not wasting the potential of the bottom end .

The truck will be my sole daily driver so driveability is my biggest concern, I do want some power but I would like to get some gas mileage out of it. The motor will be backed by a 4l80e, 3.42 gears and a 28.45" tall tires, the exhaust will probably be Doug Thorley headers and a 2.5" exhaust with either an x or h pipe. At least if I ever get bored the motor is set up to handle boost lol.

Just curious what you guys think, any advice is greatly appreciated, I at least have a full wiring harness, accessories and brains for the lq4 and trans.

[BR3W CITY]

Do you have a specific question, or just fielding input?

I like 408's, they don't push the block insanely, and you can either boost them or gas them just the same. Whats your current target compression?

A "full" port job and some milling makes the 317's flow like a much higher end head, but the milling would depend on what piston your running for PTV.

I'm "whatever" about the LSXrT intake tho. I know some people LOVE the FAST stuff, but the price tag is harsh. I really like the Hi-Ram, but its not ideally suited for every application.

[Jasons65]

Just have a lot of money tied up in the block and would hate to waste it by just throwing the stock heads and intake back on, just asking for some opinions on cam/heads/ intake but maybe I'm going a little too far with a daily driver, idk.

[BR3W CITY]

Like I said, ported 317's can flow a lot of air. Even though its a "stock" head, the work done to it sorta negates that fact. You can spend the money for something like TSP heads, but most of those start as a stock casting anyway.

Again, whats your target compression, and how is the block setup? Dished or flat or domed pistons etc.

All i can really say is that too mild of a cam on an engine flowing more-than-stock cubes will be really uninspiring. You can still daily drive a heft cam, as long as your convertor and tune are lenient enough on you.

[Jasons65]

Looked at having the heads ported by advanced induction to their 226 model, maybe take the combustion chamber down to a 64cc to pick up some compression since this will be a n/a motor, quite a bit of savings compared to a set of aftermarket heads, then would just need a cam recommendation for a 102mm tb and intake.

[Jasons65]

I honestly have to go back through my reciepts, I'm pretty sure they are flat top pistons, shooting for around 10.5 for compression, idk if that would have to have premium all the time or not.

[clinebarger]

Stock rectangle port LS3/L92 flow as good or better than "most" ported cathedral port heads.

GM CNC ported LS3 heads are $600 a piece, Keep that in mind when pricing porting, surfacing, & Valve job on those 317's

[Jasons65]

Checked the cylinder compression on the lq4 I was going to use originally, ended up checking out fine, I'm thinking there was a lifter not pumped up but all looks good so the 408 will continue its original role as going in my nova.