Hello and welcome. First of all, it is your bike, so whether you sell it to fund another or not is up to you. However (there is always a however, eh?) if you do that you will have lost a direct link to your Dad and the past. In the forum, we class 'restoration' as getting an old bike back on the road, whether it is missing a few parts, rusty, dented or restored to showroom condition, so don't worry too much over that.

I would advise starting with the engine. As said, they are a pretty easy thing to overhaul, especially if it hasn't been messed with very much. There are plenty of topics covering the overhaul, plus LINKS to other sites (all the early Bantam engines up to the 4 speed ones are pretty identical). The only special tool you really need is a flywheel extractor, though an engine stand is really useful.

Good luck.