Which is the best pick & why if you have a choice between the Colt 1911 government series 70 or the newer series 80 both nib & the same price?
Will parts & clips..etc. interchange?

the 70 series will have a bit better workmanship, much better trigger etc. mags etc will interchange. in general the 70 series will be more dollars than the 80

The 80's series has an extra parts to stop an accidental discharge. Don't remember exactly what all they added. I can tell you a 70 series has a much better trigger pull. I only own 70's style variations.

At the same price, without doubt, the 70 series.

The 80 series has a plunger and firing pin block that keeps the pin from striking the round if droped on the muzzle. The 70 series has a better trigger pull than the 80 because of the extra moving piece. How much better depends on the gun itself. Most parts are interchangable, except for the specific trigger parts. I'd handle them both if they were in front of me. Knee jerk I'd pick the 70.

I have both and carry the 80 with a good makeover because I like the added safety feature. Practice with either and you'll become proficient.