some bike part help, please

Righto.

I bought Wumpus's 2004 Chaparral Banshee frame, so I've had a frame sitting in my garage for a month or two now with no other parts, but intentions to get more parts.

I just found a sweet deal on my local craigslist for a Rock Shox Dart 2 fork. It's 100mm of travel like my current fork, can take disc brake calipers but no cantalevers (which is fine, I want discs anyways), etc.

here's the text in the post:

"Rock Shox Dart 2 fork. 100mm of travel. Lock-out and rebound adjustable. 1 1/8" Threadless. Steer tube is 7-1/2" long and has starnut installed. Post mount disc tabs, with no mounts for rim brakes. I rode 1 ride with fork then upgraded to Fox fork. This fork has no scratches or dings, a great deal for only $60.00."


Should I get it? Will it work just fine with my frame? How can I check?

So how long of a steer tube should I look for in a front fork, then? 8"+?

And if it's set up for 130mm at 6", would running a 120mm fork be alright at 6" too or should I adjust the shock/get a longer fork?

What I really want is a Marzocchi fork with plenty of travel for serious riding, but I'm poor so $60 was appealing.