I've got the same quadracer as you.  If you decide to have it built by somebody, check with Carl Bartlett.  He goes by ice racer on here.  Nobody wants to sacrifice reliability while gaining hp's, but the fact is a stock setup will last a heck of a lot longer than a racing built specimen.  Something you need to think about is how fast do you want your boys four wheeler to go?  However there are a few things you can do to improve the longevity of your motor which just so happens to create slight power increases.  Such as drilling 2 holes on the piston skirt to help oil things better.  Things like that.  I hope it helps.  The front shocks on our 85' & 86'  leave a lot to be desired.  There is a company and they are the only ones in the US, named metaltech which makes custom-to-order A arms and swingers for the 85'  &  86'!!!  Lone star quit making swingers a year ago. 
Metaltechs' contact info:
http://www.metaltechproducts.com/Metal Tech Products
6856 W. Orangewood
Glendale, AZ 85303
Telephone: (623) 915-9856
Monday thru Friday 9am - 5pm MST