Originally Posted by tjmark
I have a ls3 and ls1 sitting here and they both are the same. The only diffrences you need to plan ahead for are what oil pan you are running, and what intake your running. The truck oi lpans are deeper and the LS series pans are the shortest. Intakes are similar in height unless you go with a truck intake.
Not shure your mock up block has a starteror coil's on it, but plan room for those..
Look forward to following the build.
I have searched everywhere and just need to confirm a couple things. i have even written http://www.payr.com/engines-chevy-smblock.htm
who make the ls1 mock block but have gotten no response
are the bolt patterns the same on the back side (tranny side) of the heads. specifically, are the 4 bolt holes on the back of the heads the same. this matters as my chassis bolts to the motor via these 4 holes. i question this issue because i know ls3 heads do not bolt onto an ls1/ls6 block