[dsraven]

I have found it is best to start with one system at a time. lets start with the fuel system.

after it has sat for a bit and usually won't start-before you try to start it-check to see if there is actually gas in the carb. remove the air filter and pump the throttle linkage by hand while looking down the throat of the carb. does the accelerator pump squirt fuel into the throat of the carb? is it a nice stream or a dribble? does it jet at the leading edge of the throttle plate when it opens? if not then the jet can be adjusted to do that. if no fuel sprays then start with that repair, whether it is an accelerator pump issue or a carb drain back issue or a needle and seat or float level issue. maybe the fuel is draining back from the carb so the float bowl is close to empty so the fuel pump has to start from scratch like you ran out of fuel. that would explain the long cranking time but eventual start. anyway, ensure the fuel system is all in top working order and the fuel is fresh. I have seen a few guys that have a glass fuel filter next to the carb, when the engine is cranked initially it is easy to see if the fuel is moving through the filter, that would indicate that the float bowl has drained back and the fuel pump is supplying fuel. you can always take the top off the carb for an actual check of the fuel level issue and, while it is off you get to see what is living in the bottom of the float bowl and can check the inlet needle and seat etc. some of these old fuel pumps can have valves that allow the fuel to drain back so that could be an issue if you find you are not getting enough fuel to start at first. the glass filter idea is also a good indicator that the fuel is clean and decent color with no extras, like water, in the system. also check to ensure the choke plate actually works through a complete range from fully open to fully closed.
if all is good there next check the spark. first make sure the distributor is all good and the rotor and contact points on the cap are clean and shiny. if they have been buffed up too many times it could be an air gap issue between the rotor tip and the cap contacts. also ensure the spring loaded contact on the rotor is good and the corresponding carbon contact on the cap is good. ensure the ignition coil is wired correctly so the spark travels from the coil wire to ground instead of vice versa. there is a pos + and neg - indicator usually cast into the top of the coil next to the wire connection studs. also check the tower area of the coil for a nice clean terminal for the coil wire to attach to. I have seen that tower green with corrosion down inside. this area is also known for carbon tracking so check with a strong light and a good set of magnifiers for that. run a white business card, or equivalent, through the points to see if they are dirty. check the gap, cam rubbing block, wire insulator on the housing, condenser connection etc. check to ensure you are getting full battery voltage here because a poor connection at the ignition switch or somewhere else in the system will mean that you can receive less than full battery voltage at the coil, so you will get less than a good hot spark-less in equals less out. buy or fab a spark checker and make sure you have a nice hot blue spark at a decent gap setting-a larger gap than the plugs have. first try the for spark at the source- the coil wire that goes to the distributor cap, then, if that is good, try the spark at the end of each plug wire so you know what you have there. if that is good then check the plugs next. if they have a carbon build up, like soot, then you possibly have a ground circuit through the soot so it will misfire. also check the gap of each plug and adjust to spec making sure the electrodes are nice and shiny.
if all is good there I would next recommend a valve adjustment check. as the valves wear they actually close the adjustment lash because they wear deeper into the head so the lash goes away instead of gets bigger like some would assume.
after that, if it is hard to start, try pulling a plug, after an attempt to start with no result, and see what is going on. if they are really wet then you may have a fuel issue that just got overlooked or you are giving it too many pumps before starting, or you have the choke pulled too much or if they are dry maybe it just needs a couple more pumps or more choke pulled etc. or-heaven forbid, you don't have enough compression to make it work. when the compression test was done was the engine warm, cold? did you do an oil test to see if the compression get better when wet? were the numbers within spec?
hopefully you get it figured out.