Hmmm, just had a similar problem after my rebuild. A couple things to try:
1.) shoot starter fluid down the throttle body while someone cranks, this will let you know for sure that the you are getting a decent spark.
2.) double chk the timming, again, rotar needs to be between 4 and 5 o'clock position if looking at from the driver side facing the passenger. That should be cylender #1. My favorite way to time is the old light bulb trick. Get a meter or small auto bulb have 1 side go to ground the other go to the condenser. Make sure you have TDC perfect then turn the points till the light goes on. Back it off just a hair, and there you go a rough tune. Also chk the vacume advane and make sure it operates, mine was stuck open.
3.) Pull your gas line off your carb, stick your thumb over it, have somone crack it over and make sure you get decent pressure (mine had no pressure at all first time I tried this).
4.) If cranking even somewhat slowley but battery on charger or have someone jump it.
A few other things to chk. When you cleaned the carb just how much did you take apart. Did you completely rebuilt it or just took it apart and put it back together? Make sure that your accelerator pump spring is the right way (small side out). Also that your float isint bent to far up. If you didnt take it that far down, think about it. Also did you replace the fuel filter? The solex will run just fine, mine runs great now and even has power (not blinding speed but will do 90). You just need to be patient and give it tlc. The weber upgrade is something that is definitly worth while, just concentrate on getting this engine running first.
How did you do your compression test? Those numbers seem really low (I was getting 120lbs on all 4). #4 at 70lbs is really low, make sure you got a good seal around your tester when you did that one (it can be tough on #4 to get a good seal).
Try all of these, some of them I'm sure you already have but its always worth double checking. Just take your time, be patient, and rember how much fun it will be the car is running, light at the end of the tunnel