Don, I'm pretty excited to see that first pic.  Two things really jump out at me:

1) The tail surfaces are built-up, not sheet.  The only plan I've ever seen with built-up tail surfaces was the Model Airplane News plan, part of Jim Van Loo's original construction article in the March 1968 issue.  If this picture was taken in June of 1967, it could't have been built from the MAN plans.  Below is a picture of Van Loo's '67 NATS entry (Chris McMillan photo) - you will notice differences with your picture - it's not that airplane.

2) Also in your pic #1, notice the shortened elevator counter balances. 

3) Also the canopy appears to me to be a standard "bubble" type canopy, not the same as the canopy on Van Loo's '67 Chipmunk in the McMillan pic.

So was this airplane a Chipmunk design by someone other than Van Loo?  Or is it Van Loo's very first one, that he took along to the NATS as a backup?  It's a mystery.

Jim Van Loo's 1967 NATS entry (Chris McMillan photo)

The reason I thought this Chip belonged to Bob Welch...it appears to have a wing that has a slight dihedral? Which would mean that this one is Welch's but this slide doesn't give a good view to see whether or not this model contains that or not?

Jim, the number on the rudder is off the full-scale Hal Krier Chipmunk.  It's not an AMA number.

Don, in your original post I missunderstood and thought you were saying that only the second pic was Bob Welch.  Now that I look more closely at both pics, I think you are right.  The wingtips look identical in your two pictures.  Must be Welch's airplane in the first picture too.  So then his Chipmunk pre-dates the Van Loo magazine article!?

I have Bob Welch's and Joe Dill's E mails and phone #s and this will certain clear up if this is Bob Welch's beautiful Chipmunk.

 Joe and Bob...often flew "pairs" these two models. Both of those models going through a modified flight plan was AWESOME!
Both Joe and Bob took away some pretty good top 3 place hardware from the rest of us in those old daze day's of the 60-80s!
for more info on these two amazing CLPA'rs...go to our search engine and type in "Joe Dill" and "Bob Welch."

Jim,
The information I got in talking to Jim and Mike is:

Jim's 1967 Chipmuk(s)  - wood wings, 57" span
Jim and Mike's 1968-69 Chipmunks - Foam Flite wings, 55-1/2" span (I measured Mike's myself)
MAN plan - wood wings, 54" span
SIG CL-3 Chipmunk kit - wood wings, 54-3/8" span

They all used the same root and tip rib templates.

Mike

Interesting Mike,

Then you could build a Chipmunk wing in either 54",  55 1/2" or 57" using the root and tip templates and be perfectly classic legal!  The 55 1/2" version is the 1969 Nats senior champion version though!
Jim Pollock    

Another scan of the 69 nats line up...Hey, Must be Mikey's model at the front of the pack?
Maybe not...here is a close up shot I took with my old SR-2 and Kodachrome 10 and the canopy looks different than in the first photo? Note the DARK TINTED CANOPY, while the shot I took of Mike in the last shot..the canopy looks Clear? Humm?

Yeh..Mike!
I see what you mean...and I agree after looking at that slide under my 20 power magnifier that is indeed... Stott's ride.

Who is that skinny guy walking by in the background? I thought he was a banded fly from the past.

Don't have a clue bout' the skinny kid...but THAT HAT BELONGS TO YOU...LEO!!!