I've had pretty good luck using a gb14c40L IGB ignition driver, insulated gate bipolar transistor, for a driver, hooked up pretty much like the datasheet recommends. I think I leave off the diode acrossed the coil. I use a resistor coil from a 12 volt automobile ignition. I switch the igbt with a hall effect switch, points will work too. Regardng hall sensors, there's generally two types, switch and latch. You need a switch. They're a dollar or so from digikey. Buy a bunch cause you're gonna burn out a few getting the bugs worked out. Some things to watch is to be sure to get a hall effect sensor capable of handling high ambient temperatures. At first I didn't think about heat causing problems but with hall effect sensors heat matters. I use 125c ones. Higher temp ones get quite pricy and I don't seem to need them. Also, to help prevent emi from blowing out the hall sensor add a 20K 1watt resister in the HV lead from the coil. Use 1 watt cause its physically large enough to keep the spark from jumping from one end to the other. I control dwell with a shutter. Lots of web sites suggest placing a south pole magnet in a disk on the crank or cam but they don't account for adjusting the dwell. Use a steel disk with about a 22 degree slot running between the magnet and hall sensor, on the cam of course. A shutter on the crank reqires wider slot. That gets the dwell in the ball park. If the hall sensor is in a distributor I add some low wattage, for small size, zener diodes directly to the hall sensor to protect it from emi. TIM seems easy but its not. Its the best way though for a small engine. Points add a lot of drag and too mounting the cap is always an ugly problem. I get most of my parts from digikey.
On a hit'n miss its pretty easy too to add a second hall effect sensor parallel to the first to the valve pushrod, use a shutter here too, to keep the unit from firing during the coasting period. That'll extend battery life a lot.
Good luck.