Wouldwork

Hi all, I'm hoping for some help to figure out the best strategy for buying some machines to complete a construction project and set up a shop.
I am building a barn and I'm milling the wood with a small bandsaw mill. I want to get a 20" thickness planer that can punch out all the siding and flooring.
I've found some options and now have gotten myself dizzy trying to figure out the best way to go. Here is what I've found:
A shop that is closing and selling a Delta rc51 asking 1800.00. They also have a SCMI 12" planer that looks very nice and a powermatic spindle shaper that might be perfect for putting the halflap and tongue/grooves on. They said they were negotiable on price.The machines are 3 phase.
A rc51 asking 1400 -negotiable and an older unisaw for 450.00. They are 1 phase.
A "like new" dc580 they are asking 2000.00
A rc51 asking 1600.00
A "like new" Grizzly for 1000.
And some others.
Some of my questions are: Should I not bother with 3 phase conversion? Should I consider buying the 3 phase machines if there's enough of a discount so that I can buy 1phase motors and sell the motors that are on the machines now?
Are the rave reviews on Byrd heads well founded. One post said "don't buy a planer without a helix head..." If I bought one of the rc51s I couldn't afford to upgrade (2000.00).
Should I avoid the automatic bed raise and lower on the rc51 because it is something that could fail and I don't mind turning a handle which is a simple reliable way to adjust height?
What are the differences between the dc580 and rc 51 delta planers?
Should I buy a new Grizzly for 1500.00 and be done with it?
This is getting too long. Thank you for any advice you can offer.
Bart