Here is a problem you will face on the 5.7 but not the 6.1 as well. The dip stick tube is supported by the first bolt in the header but can't be bolted back due to the difference between the manifold and the flange thickness.
You could run a 6.1 dip stick, which would have a longer support bracket, or make up a spacer like I have done. I decided to use the original manifold bolt and cut a spacer from this solid bar I had.
Bored out the spacer after cutting it to length and used the nut that held the old heat shield on to keep the dip stick tube in place instead.
Also just could have used a longer flanged bolt like the other new ones too.
Bolted on the mid pipes that came with the headers. These now end with factory flanges and in the same position where the stock 6.1 SRT8 cat back system bolt on or after market ones.
These even cleared everything! Seems a shame to cut them up to fit real cats in place! I ordered without cats, $200 cheaper, and they just have these fake ones instead. You can order with their slimline cats but they will throw a code just like nearly every other after market cat on the later models. Only factory cats wont and some sold now by Kooks. So I will have to find someone with good tig skills to weld some in for me as not worth setting up my mig for this little job.
Was able to run all the O2 sensors in place as well after cutting a couple of ties that were holding the plugs to the loom. The furthest one I might buy an extension for. Make sure you label the plugs on the loom side as very easy to plug a after cat sensor in a forward cat one and get a bunch of codes as a result!
The cross over now happens to the rear of the transmission pan instead of in front of it. I'm not so keen on the cat placement under the pan, so when I fit the factory one, will add it further along on the other side.
Got the original front driveshaft lengthened the amount I moved the engine cradle forward, so now can see if it clears everything. Plenty of clearance over the cross over pipe.
Misses the header too so all good to go.
Who would have though all this would bolt up to a 5.7, even though for a 6.1, and in a 1948 Willys Truck frame!