1987-1998 Suzuki Quad Runner/King Quad 250/300 Service Manual

Hi, I'm a newbie on here.  I just got a 2007 Suzuki KingQuad LT-A450X.  Are there any specific issues to look for on this model?  Any specific maintenance to do other than the usual oil and filter changes?  
Thanks

Just bought 06 KingQuad 700 and first ride out hit a mud hole, not to deep and it shut off and would not start. 
Got it home and found the spark plug hole was full of mud and water. Went and bout a new spark plug and began cleaning it out. Put a deep socket in there and it wouldn’t grab. Took a pic with my flash and this is what I see. Any suggestions? And what is it??
 
previous owner said it had a new coil so that’s why I decided to change out the spark plug, also ordered new coil should be here by the weekend. 

Ok, so I bought this scream of a deal the other day - a 94 King Quad 300 for $40.00.  It's been sitting outside with no carburetor on it for about a year.  Its rusty, missing some parts, wiring is all cut up and spliced etc.  No seat, no racks but the plastic is all there minus the headlight housing.  Anyway, who can pass up a $40.00 quad right?  I get it home and looked at the sight glass for oil level, it's about 1/2 oil and 1/2 water.  I drain it, refill it and turn the motor by hand (recoil starter is missing) and it turns over just fine.  I worked on the wiring for about an hour and got it to turn over with the electric starter and got enough of it sorted out to get a spark.  Did a quick compression test, 70 lbs.  Wet test bumped it up to 90.  Ok, so rings and cylinder washed out with water for a year, not too surprised.  I thought 'what the hell' and sprayed some starting fluid in it and it ran for about 2 seconds - enough to show  it's got life.  Since then the compression has gotten worse, I can't get enough pressure to activate the carb diaphragm, therefore no fuel pump either.  The compression is now around 60.
  Anyway, my question is....is it worth it to try to get this thing going?  I tore the top end down today and the cam and one of the rockers is pretty worn.  I figured a top end job would be about $100 or so, depending on the condition of the cylinder but I'll probably have to put a cam and rockers in it as well.  Doing some research on ebay I figure I'll have to spend about $500-$700 to make the whole machine right again.  Much less just to make it run and use as-is but I won't really like it until it's right.  I don't mind doing the work, I actually enjoy it but I'm concerned about what all that water did to the rest of the internals, I can't really test it all out until I can make it run.
I know it's a basket case but I'm not into it much at all, even if I do the top end and find something else wrong I'm still not out much.  I'm leaning toward ordering the top end parts and going from there unless you can convince me otherwise - any way to check the rest of the internals without tearing it down?  I plan on flushing the oil cooler before I do another oil change, I've drained it twice now and it gets milky almost immediately just turning the starter - I suspect the oil cooler is polluted badly.
 
I'll get some pictures today if anyone want to see them.
 
thanks!

Looking to purchase a windshield for my ATV, suggestions of what to buy with quality in mind and will fit without doing any modifications. 

I've got a king quad 750cc has anyone converted the fuel pump relay to a stronger fuel pump relay on there king quad?