Great looking bike, bud! I have the exact same one. I got it in almost the exact same way (milage, price, etc.), and undoubtedly the same running condition (would start but not stay running, running on one cylinder, etc. I really like your new tank! Seeing it made me check ebay; I love the boxier look of earlier xs models.
You want your cylinders even and 150 and above. Re-test to confirm that you have 150 each. Search for "compression test how to" or something to that effect and find it on the site. Not sure what he was referring to when he said hand test.
You will certainly need to check your valves at some point, and if it ain't running, it ain't hot! Let it sit cold overnight, and test it before the sun hits it. Read like 3 threads on valve adjusment, and compare and contrast them all, look for the good tips and the trials and tribulations of others (not to make the same mistakes!)
You didn't say anything like "I installed an inline fuel filter...." so I assume you haven't yet. Do it. This is one less thing to go wrong in your tuning. Do it next, and before you clean your carbs again.
As for the current running condition - definitely lean. It is either an air leak (which bcware gave you the right idea on how to test for that) Or, it's your carbs. The carbs need to be meticulously clean. I personally don't think any other approach (except maybe boiling, which I don't like the idea of) can remove the "tartar" that has accumulated on the inside of your carbs aside from scrubbing. Pay special attention to the jets, because that is where the fuel is the business end of your carb. The pilot jet (the portion with the 16 tiny holes in particular) are one of the main places where grubby carbs can cause issues (especially with idle, starting, etc.).
How do you "scrub" these jets you ask? Try finding "wire gauge cleaners" at your local hardware or auto parts store. Not everyone has them, but they are a set of ribbed wires in different gauges from tiny to about the size of a virginia slims cigarette. These help to clean the inside of these jets really nicely. If you can't find them to buy, I've heard of people using guitar strings of various sizes, and just about anything stiff enough to get a nice abrasive scrubber for these tiny passages.
I believe you when you say you cleaned your carbs - but in this case, my guess is that the jets need more attention. Make sure you can see the inside of every passage. Hold them up to the light, and look for the inside to look smooth and continuous (not rough from a layer of plaque.)
Do your leak test before you pull them off, but if you pass the leak test, clean your carbs again.
Go ahead and change your old fuse box to a $5-10 blade type fuse box from your local auto store. The stock tube style is notorious for having the springs become brittle, leading to weird electrical demons.
After you got the bike running solid, you will probably have the mufflers go bad on you. The baffles become loose, and are non adjustable (they are tac welded in, and with the age, the connections soon breaks from vibration). Make sure you are confident that you get the bike running properly and confidently, then plan to replace your mufflers (requiring a re-jet of the bike, which is why I recommend you get all the adjustments right first. You need to know how the bike runs and sounds, pulses, etc before you go and change it drastically with new pipes). I used emgo shorties - as cheap and as loud as they come aside from maybe slash cut or straight headers. I may change them one day, but I love the grunt these give.
If your bike is like mine was when I got it, you will also find your charging system to be inadequate, or working improperly. Run the diagnostic located in the manual to determine whether it is or not. If it's not, then there are a few good threads you'll find if you search. This forum, good search skills, lots of reading (and some of my own trials and tribulations...) have got my bike from where you have yours now to where mine is now (running solid with confidence, moving on to fixing up the cosmetics and minor details). Bought mine with a bit under 8k on it, gonna hit 13k in a week or so. What started as a project for me became one of my most favorite bikes I've ever owned.
Cheers, and good luck!