LT1 swap info... rookie questions, just want to be sure

[coyote11]

I'm swapping in a 1995 Lt1 and T56 into my 1967 Firebird. I've heard some get the PCM reflashed, I've heard some say it's not needed. I am deleting all EGR, no need for it. I really don't care about codes it may throw. I did hear that if it throws a code the cooling fans will always stay on. I also know VATS is in there, but they make modules too. Is it just better to reflash it?

I'm also considering doing my own stand alone harness, I have every piece of wiring out of the donor car, and every sensor, I stripped it bare in my garage. I've heard, it's not so bad, and I've heard it can be a pain. Is it just miles ahead to buy a harness for the conversion?

I'm doing everything on a budget, trying to be successful at a modest pro touring car. I know budget is relative, but I can safely say a $400+ harness seems real spendy when I have a harness on my garage floor.

I'll take opinions and recommendations. Oh yeah, I know I have to get chevy engine frame mounts, and a custom T56 compatible tranny mount.

Thanks to all.