I know this has been asked before but I need some good advise on this. I will be using the stock A-arms for now. Just seems like a tubular k member would make things a ton easier for the swap. This is a car that will be driven daily but not every day, it will see high speed duty and some drag use. So please share some info with repect to my swap descision.

 

Stock K-member can be used under some conditions

Fbody LS1 oil pan is a must. Using 1" setback adapter plates with SBC mounts or spohn swap mounts it will clear, but only just barely. Several people notch it anyways. I didnt notch it the first time but if I were to do it again, I would cut it

LS1 AC compressor requires a notch. Non-AC swaps or those using the custom bracket to mount the 3rd gen or aftermarket compressor up high on the pass side do not require a notch

 

How close is the engine to the A/C box when the engine is set back?

 

It isn't the front/back that gets close to the A/C box, it's the ignition coil. Truck coils mount up higher on the valve cover than than f-body coils, so the truck parts are often used to get the needed clearance.