Yes, its the 1989 Comet Miniatures model kit. I still have it, in excellent condition.
You might also considering making the other variants as well. There was a Destroyer variant that didnt have the three outboard projections, just the drive section.
The Scorpiio was a modified freighter, although it didnt look too bad, it just wasn't the Liberator lol
I'd like to see someone do the Eagle spaceship from Space: 1999 as well. They would be about the size of a PF.
The Liberator, by the way, was a very large ship. In game terms, it has shields, transporters, a lot of hull and cargo space and was designed for deep space exploration as well as combat. Its primary weapon was a neuton blaster housed in the nose of the ship, although I always thought the outboard projections looked more like huge ship mounted Phaser-IVs. This ship should be about the size of a Dreadnought.