If you're taking a run at this as a tinker/figure things out...it's definitely worth that. But I'd caution about setting your expectations appropriately and not letting the costs run out of hand. It's not possible to turn a pigs ear into a silk purse without basically tossing out 95% of it...and that's just not cost effective.
1. Start with what you've got...complete strip down of every part. Become familiar with how all the little bits of both the mechbox and body go together. From the front sight screw that can dent/pin your inner barrel to the crappy pice of tape that holds the sling swivel to the body to the massive amounts of unnecessary grease in the mechbox. Go over the wiring layout and connectors, etc...
2. Work on the stock mechbox as is....but aim to replace the plastic bushings (the old ones had plastic bushings) with solid metal bushings (not bearings)...and the spring guide if it's flimsy plastic. Hold off on all the other upgrades until you've got a good handle on compression and shimming.
After you've done those two things....you'll have a solid understanding of what makes that particular AEG tick, what it's good and bad points are and where you want to take it from there.
THEN...I'd recommend you get a mid-level nice AEG and give it a once over. You'll be able to easily ID what make one so much nicer than the other.
Best of luck,