need some advice, non running 82 kz 550 ltd

Any help here will be much appreciated, ok a little back story on the bike, I got it off Craigslist for cheap, guy said he had the motor apart due to no compression on cylinder #2, found an rtv sealed head gasket, pulled it apart, de-glazed the cylinders, new gaskets, then just set stuff together, after I got it, I put it in time, torqued down the head, cleaned out the carbs, finished assembling the engine, and now i cant seem to get it to fire, I have spark and compression, and even using starting fluid its not starting, it acts like it will but never does.... Any ideas will be very helpful. Thank you for your time

Make sure your primary wires on the ignition coils are on correctly and the plug wires. Do you have a manual for the bike? If not member loudhvx has a pdf version in his signature also a web site for the 550.
copy and paste this entire link in your browser.
home.comcast.net/~loudgpz/GPZweb/Mnls/Mnls.html

I do have a manual, I checked and the coils are hooked up right, and the wire are correct as well

Run a compression check. If the numbers are very different from each other or very low, double check your cam timing.

Found why it wouldn't start, compression test came back with #1 50 psi #2 15 psi #3 30 psi and #4 30 psi

Bummer on the compression. Since you found the bike on CL and had a head gasket covered with silicone, did the Po get the cam timing off and bend the valves? Sounds like the PO had no Idea. About all you can do now is verify the cam timing, then do a quick check of the valve clearances. Then if the compression is still bupkiss, you'll have to pull the head off again.

Well i was finally able to re-do the compression test, added oil this time and all cylinders accept number 1 basically doubled, so its time to tear it apart.... But where is a good place to get engine parts for this bike??

Have you pulled the valve cover?/ Checked Valve clearances, verified cam timing??
Depends on what you need for parts. z1enterprises.com will have gaskets rings and valves/ guides. Not sure about pistons.
Make sure your not chasing something easy, like valve timing or tight valves, blown head gasket etc.
You can do a Leak Down Test to see where the compression is going.