[quote author=djchris link=board=1;threadid=4482;start=msg33557#msg33557 date=1061414980] are they? [/quote]
Darn close. The latter model 2F's in the 1979+ 40s I believe were quite close, there were new AC/PS mounting bracket holes in the updated 2F blocks (maybe the head?) The pistons in the latter-latter-model 60s I believe were also different, but I defer to those more knowledable for that.
Many other things changed in terms of accessories such as the carburetor, AI system, distributors/ignition throughout the years, et cetera. Most things are completely swappable though going up in years.
[quote author=djchris link=board=1;threadid=4482;start=msg33568#msg33568 date=1061418153] What about power--torque, HP [/quote]
Some specs I only recall, but can't find them when I read your post. IIRC, the 85+ (maybe I'm incorrect on the year, maybe earlier) had 10 more HP and 5 more lb-ft, I'm assuming dead on in the RPM range. This may be due to a slight change in the head at that time, again I'm speaking from what I remember when I used to try to memorize some of this, but its been a while.
Someone will definetely know exactly HOW the head changed in that year.