You are asking about the single most variable Colt model ever made...
Is the lower a slab side or later raised A2 style?
Is it large or small pivot pin?
Does it have small or large trigger pins?
Does it have a sear block?
A2 upper receiver?
Bayonet lug?
Is it an original and completely original gun?
The prices sounds good but with the right combination of features this gun could be really special or something that could frustrate you in the future.
If you don't own an AR15 yet, personally, I would want a Mil-Spec lower over one of these but that is to allow any current or future accessories for the AR-15 without needing funky adaptors, chopping out blocks or adding sleaves to fix gunky pin sizes.
Now, if you really want a Colt, well then you already have your own answer as Colts are unlike all others as only Colt screwed with their guns so much and you are asking about the most screwed with of all screwed with! This is what is refered to as the "transition model colts" because of all the changes.
Some were really great because they got close to being like a Bushmaster, RRA, DPMS, Eagle Arms, Armalite, etc... But none are 100% standard parts unless you find one of the ultra rare white label guns but those I expect are in personal collections and have been so for a LONG time now!
Good Luck!