95 TRX300 Rear Shock replacement?

Hey guys, I just got a 95 TRX300 2WD and spent the last week working on it getting it ready to ride. Last night I got on with my wife and the rear fender almost touches the rear wheels. Now I’m a big boy (6’3" 270lbs) and my wife isn’t tiny either so I pulled the shock and noticed there is no adjustment for ride height, preload, etc. so I looked online and found there is a progressive type shock I can get that adjusts http://www.ebay.com/itm/1993-2000-Ho…VVjEPx&vxp=mtr

So my question is will this shock provide the desired adjustment for ride height to keep us off the back wheels? Or should I look at a more expensive 512 series shock?

Thank you!