Z1 Motor Condition - How to Check

I picked up a Z1 motor sometime ago that had supposedly been rebuilt. Before I fit it into a project I'm working on I was wondering how I could check the condition. I was planning on checking the compression using the kick starter but wondered what other checks I could perform before I put it into the frame - leakdown? Any advice is appreciated.

Pull the cam cover , check the clearances and general appearance.
Pull the sump and check for anything visually untoward and for crap on the oil pump strainer.
Do a leak down test and comp test just to see if they are in the same range but you need to spin it on the starter to get a true comp reading.
Doing it on the kicker is a waste of time.
Anything wrong on these engines is usually top end so if it all looks good stick it in the bike and you can easily sort the top end later if needed.
Other than that you should do a complete engine strip and check as the bottom end costs virtually nothing to pull apart and reassemble if all is found to be ok.
Personally I just bite the bullet and pull them apart.
If i'm spending money on a project the first thing I sort out is the motor.

Agree on checking valve clearance before moving to a compression and/or a leak down test.

Best bet is to try it but there are some things to check before putting it in. Agreed to all of the above but youll never know the condition of the valve seals and rings unless you tear it down or try and run it. Also, leak downs and compressions can look extremely bad if the motor has been sitting a long time and you have rust on the valve angles. First time you fire it up that all goes away though.
My biggest thing in using an unknown motor is the trans. Ive been burned twice putting a motor in and then finding out the first time around the block second gear is gone, out comes the motor again! Take the pan off and inspect the condition of the gears and dogs before you put it in the bike.

... and compressions can look extremely bad if the motor has been sitting a long time

Yes I've noticed that too on several bikes . The big unknown being of course is it sticky rings that will it sort itself out within a few minutes or a tank of fuel through it, or is it a top end rebuild?

Thanks everybody.