Here are some interesting if somewhat crude frame measurements. If you line the mid-60's frame and an early 70's Bottecchia frame up at the bottom bracket shell, the seat tube, down tube, and head tube line up pretty well. The older frame is an inch smaller in size (perfect fit for me) so the top tube sits lower and the head tube is a bit closer in but that would be expected. What is note worthy are the significantly longer chain stays and consequently slightly longer wheelbase despite the smaller frame size. I'm not sure how that will affect the ride and handling characteristics but it does show that even the big factories like Carnielli were following the trend towards shorter chainstays and wheelbases by the late 60's.

Mid-60's (1967) 22" Bottecchia frame measurements
Frame weight 4 lb 12 oz (2165g)
Fork weight 1 lb 11 oz (767g)
Size, inches 22
Seat Tube, mm 565
Top Tube, mm 570
Chainstay, mm 457
Wheelbase, inches 41.5
Head Tube Angle,° 73°
Seat Tube Angle,° 73°
Seat Post Size, mm 26.8

Boom Period 1968 - 1974 23" Bottecchia frame measurements
Frame weight
Fork weight
Size, inches 23
Seat Tube, mm 585
Top Tube, mm 585
Chainstay, mm 435
Wheelbase, inches 41.0
Head Tube Angle,° 73°
Seat Tube Angle,° 73°
Seat Post Size, mm 27.2