Welcome to the forum...I have a '79 as well.
You probably need to tell us a bit more about your bike situation...otherwise we're guessing blindly.
I assume it ran last summer? Any issues before you put it away? Did you drain the gas? Since it's custom, does that mean kick-start only? Running a capacitor or is the electrical/charging system stock? With a '79, it would have come with BS38 carbs...are those still there or have they been swapped out for something else? Basically, what does a hand-crafted, one of a kind bike mean with regard to running parts, etc?
Does it sound like it's trying to start?
You say you have fuel...A '79 would have vacuum petcocks...have you checked fuel flow from the tank? Do that float bowls fill up, and you've checked that the carbs/jets are clear--are they fouling the plugs after a few attempts at starting? Choke on/off any difference?
You say you have fire...you're referring to spark, correct? Or do you literally mean fire out the exhaust?
If compression is an issue...have you done a compression test?
Have you gone through a full tune-up?