Technically there is no rule to dissallow anything
HOWEVER there are clear indications of what is accepted, and allowable
From my perspective both changes you are proposing are outside the spirit of the event....

Couple of problems here.

The PAMPA rules for Classic Stunt include:

"It is expected that contestant will comply with the spirit of the event and enter only qualifying models which as closely as possible accurately reflect the aerodynamic layout and appearance of the original.    .... removable landing gear which allow the entrant to adapt to the contest site and conditions are allowable.  This would not allow the substitution of a tricycle landing gear for a conventional gear, or vice versa."

The Shark has a tricycle landing gear - period.  Unless there is proof that somebody flew a Shark prior to 1970 with a conventional gear, a Shark equipped with such a conventional landing gear should not be allowed to fly in the Classic event.  Furthermore, unless there is proof that somebody flew a Shark with a retractable landing gear prior to 1970, a Shark equipped with such a retractable landing gear should not be allowed to fly in the Classic event.  Using a retracting gear in a Shark may or may not improve its performance, but the "appearance of the original" in the air with the gear retracted would definitely be changed.  (You might find an ED who thinks differently, but he would not be acting in "the spirit of the event".

Now, for another matter.  As mentioned above, a retracting gear on the Shark may or may not improve its performance.  There would definitely be some differences in the manner the model is trimmed to perform the stunt pattern.  Would it look neat?  Definitely!  There should be no reason not to use a retractable nose wheel if you want to go ahead to build a Shark (or any model with a tricycle gear).  There are light duty electric retract systems that has a nose wheel that rotates the strut as it retracts so that the wheel would be flat against the tank.  These are available as a system from some of the RTF RC manufacturers.  Besides, these systems are much lighter than anything from E-Flight and should be strong enough to work with a comparatively lighter model (like the Shark) than the RC models the E-Flight systems are built for.

The RSM Shark kit is a good kit.  If you really want to build the Shark, fine.  But if you want to build a really neat looking Classic ship with retracts, you might want to look at Harold Price's Crusader.  It has a conventional gear with retracts.  There is a photo somewhere of such a Crusader at last year's VSC.

Keith

Again, thanks all for your input here. I apologize for the two running threads on this topic. I'm just so enthusiastic I can't control myself (lol).
Keith I like the idea of the 90 degree rotating retract for the nose gear. Makes sense.I'll try to find the pic of the Crusader,but really love the look of the Shark.
Doc, I'm not a Pampa member and need to do that immediately.
I keep reading about the vibration of the ST60 and that might be a consideration  regarding the nose gear and these light weight electric gear. I've got a lot to think about here.Thanks guys for everything....PhillySkip

Keith thanks much for taking the trouble to help me out. I'll go to that link now....PhillySkip

http://www.airplanesandrockets.com/magazines/control-line-capers-september-october-1963-american-modeler.htm

Saw the plan on google pics the other day . Not Now though . Maybe was hipocket or the other one , Im Thinking .

Matt   I use to attend the contest mentioned in that article at Ithaca NY. It was held in a park on Lake Cayuga on rt96. Article mentions wind and that was a windy spot.
I can not remember the Crusader in the picture.
Ed