71 C10 LQ4/4L80E Mounting Questions

[SabbathFanatic]

Hey guys, got my front clip pulled off as an assembly last night. Other than one of the core support bolts being a pain, that was ridiculously easy. I love this truck! Pulling out the 350/TH350 combo this afternoon. Got a few questions for planning the next stage of the build once my LQ4/4L80E combo gets here next week.

My plan for moving the crossmember is to measure from bellhousing face to trans mount on both the TH350 and the 4L80E and move the crossmember whatever the difference is. Got a few questions for people who have done this before:

1. The engine mounts I'm using can put the engine in four different places:

• Stock location
• 7/16" forward
• 1-3/4" forward
• 2-1/4" forward

I'll have to take whatever placement I choose into account when I'm calculating distance to move the crossmember. I'm not using A/C, so my understanding is that the placement should only matter for header clearance. I basically don't have any money after buying the engine/trans, so I'm going to use some of the cheap eBay LS swap headers. Do I need them before I choose where to put the engine? I'm thinking stock location so the shift linkage lines up right. What is you guys's experience with engine placement and header clearance issues?

2. I've got the front clip off, and the bed is coming off for the fuel tank. Is it worth it to take the cab off too? It seems like that would make crossmember relocation and engine/trans install way easier, but it would also mean I have to redo the front clip alignment when I put it back on. I also wouldn't know about any firewall/trans tunnel clearance issues until I put the cab back on. Opinions?