Fair enough, that is one good thing not buying off the shelf. You can put together whatever suits you best. Find nice hills if you have no bail out gear
You are doing it the right way. Free is good 4 letter word and much better than work.
Keep an eye out for donor bike too that might pop up Gumtree / Ebay / For Sale / Cash Converters forums etc that you can use to graft components onto you new steed. The unfashionable 26" stuff can be had for bargain if you are patient and don't mind scouring places to find.
I'll have to admit that GT's product line sure did get confusing. The alloy Avalanche's Agressors and Panteras were made in Taiwan but some of the cheaper and later model ones again could be from China.
Some bikes were much the same but different features such at the Richter 8.0 which was one of the first with Rock Shox front suspension but had plain gauge tubing (much like the Timberline and below) to keep the costs down.
The serial numbers can give some hints too and the leading 'H' like on my green Justin Timberline signifies the Hodaka plant
http://www.hodaka.com.tw/ that made them for GT among other companies. They did a good job since I think the only way to break that frame would be to run over it with something heavy.
I think the Outpost was the bottom line then the Talera. I had a Talera as my first ever MTB when I lusted after the more expensive stuff but couldn't afford nor justify saying to the folks 'it only cost me $2.5k' without getting sent to doctor immediately afterwards.
Saying that, I had loads of great times on the Talera and wouldn't have changed it for anything as it introduced me to messing around in the mountains on a bike.
Here is link to the GT catalogues that listed the bikes and model pecking orders for each year in the 90's. They did make some great stuff when you look back at it all.
http://www.retrobike.co.uk/gallery2/v/Manufacturer+Archive/GT/Catalogues/
Stuff like this made be dribble for the 92 Avalanche which I pulled the trigger on eventually.
http://www.retrobike.co.uk/gallery2/v/Manufacturer+Archive/GT/Ads/Avalanche/GT+Avalanche+1+800.jpg.html