Sounds fishy to me!
How about boring us with every little detail of your build?

 

fugg it, Go LSX , 6 bolt heads, 106mm, and 30+ pounds of pressure LOL

 

If money was not object that would be nice. Unfortunately it is and the biggest I will probably go is the 408.

 

What was you pressure? what boost to back pressure ratio did you see? and what turbo(s)?

 

If money is an object go with the smaller cubes, both setups can yield the same amount of power safely.
I can understand justifying one over the other if you were basing your decision around parts already purchased (turbo, etc)

You will save 1000.00 off the top by going 370 vs 408

 

Put a T76 sized turbo on the 370 and turn the boost up. If you have the turbo setup why worry about the cubes and extra money to make the power.

For your goals a 370 is MORE than enough.

 

408, more power down low and less boost means it should last longer. PM sent

 

"it should last longer"

Trust me, the internal parts do not know how much boost he is running.
HP is HP.. both of these setups can be built with the same reliability.
They dont rate turbo pistons by PSI, they do it by est. HP along with other internal parts.

Zombie on Ls1tech has a 370 that he literally pieced together from the classified section.
He is around 800RWHP
Here is his engine components!

"Set of used 4.030 diamonds I got used for $200 and a $200 set of total seal rings. Rods are Eagle SIR 6.125 I-beam SBC rods I picked up for less than $250ish. Stock crank. Been running this setup for 2 years now."

https://ls1tech.com/forums/9038779-post7.html

How is that for reliability

____________________________________________
You will be pleased either way you go...

Go with Diamond or Wiseco pistons, they are proven many times over.
I prefer Wiseco because they come completely de-burred and ready to install after cleaning. If the machinist has to prep the pistons it will add up on the machine work $.
Wiseco out of the box pistons are rated over 1K hp as well
The top ring is also fitted lower on the crown which reduces exposed heat to the ring..

Compstar rods over Eagle... Compstars are ready to install out of the box 100% of the time, Eagles caps sometimes need machining which can add up on your machine work cost.


Diamond or Wiseco Plasma-moly select rings will work great!

Try the new 5 layer LS7 head gaskets, they will seal better!

 

I was saying that at a goal hp the 408 could make the same power with less boost and less of a max effort to acchieve the same power, right? Say you have a goal of 600 hp it would take a 370 15 psi, and the 408 could make it maybe with 11 or so. I am just thinking out loud, plus you could run the same cam in both and the added cubes would help tame the cam more in the 408 vs. 370. Shouldn't the extra stroke be worth more low end as well?

 

Why would it take a 370 15 psi to make 600HP? I assume we are talking rwhp here....and I have seen several 5.7L Corvettes make 600 rwhp on less than 12 psi. ****, they can make 550 on 10 psi and the right cam.