Dart Powered Mustang and Piper Enforcer

I had been reading through a back issue of Australian Aviation Magazine -
September/October 1987.
And came across an article about the development of the Mustang.

The picture of the Dart powered Mustang had this caption....

Quote
Well known to Canberra residents for many years this Dart powered Mustang
never got airborne under its turboprop power and is now being rebuilt to
standard D specs.
Un-quote

(Just for the record Canberra Australia is located in our state of New South
Wales and bears the international code YSCB)

The Dart engine looks like it was lifted straight out of a Vickers Viscount
or similar.

**************
The caption for the Piper Enforcer reads....

Quote
The final version of the long lived Mustang was the Piper Enforcer. This
Counter Insurgency aircraft was powered by a 2445shp Lycoming turboprop and
was optimised to deliver up to 5600 Lb of underwing stores while operating
out of remote and semi prepared strips.
For a variety of political and and technical reasons the aircraft never got
past initial developmental funding and the two Enforcer prototypes presently
remain in storage.
Un-quote

Does anyone have any further information on these two interesting types.

With apologies to the folk on dialup - I couldn't get the images much
smaller.

Graham