I did drive down to Oklahoma to pick up my lathe, 3400 mile round trip.
Max through a 16C is 1 5/8, could go bigger with an emergency collet, but not through.
I would just buy a spindle assembly,that way you can get the whole assembly many times including the collet/chuck closer. Here are a few examples from a quick EBay search.
https://www.ebay.com/itm/TSUGAMI-CNC...AAAOSwtfhYnI1D
https://www.ebay.com/itm/TSUGAMI-CNC...sAAOSwCU1YnI6p
https://www.ebay.com/itm/Okuma-LC20-...EAAOSwHPlWdEdk
https://www.ebay.com/itm/Mazak-Quick...wAAOxyfCBSB79I
https://www.ebay.com/itm/Mazak-Slant...kAAOSwm8VU0P7O
That would be my choice. I wish I had a C axis spindle on mine, but it's going to get that one day. I have a design for an auxiliary drive system using a 1.8KW servo. A 7.5KW servo is expensive. I've been trying to find a used one at my price.
Seems well within normal operation envelope. Don't short yourself on motor power.
That's about what my lathe has, has been adequate for everything that I'm doing. I think my longest part is about 4 inches x 1 1/2 dia. I could easily turn 10 or so inch diameter. Depending on how many tools you need to run with gang tooling,10 inches of X may or may not be enough.
I have been running with 5 inches stickout on the part above, 6061 aluminum, no problems. The stainless parts I run a bit closer, but they are smaller.
As I said above, max through a 16C is 1 5/8, but there is another collet system that goes up to about 3 inches. I haven't priced them but I'm assuming it's not cheap.
https://academy.titansofcnc.com/seri...p-collet-chuck
I think my ball screws are 20 or 25mm can't remember which. 10mm lead as I recall.
Steppers would work, but you are really talking about a pretty big lathe, and servos are not that much greater in price unless you are comparing to the cheapest EBay steppers.
I'm using 1.8KW DMM Tech servos on mine, they pretty much match the performance of the original Fanuc servos.
https://store.dmm-tech.com/products/...ac-servo-motor
This is not a recommendation, but rather just to get the creative juices flowing. A nice picture of a small slant bed showing the guts.
https://hirung.en.made-in-china.com/...-Tool-E35.html