I don't have a power adapter to offer you, but this Apple KB article will tell you what model Apple power adapters work. It doesn't get into deep specific specs like you were asking about but someone else will come along with that info I'm sure. Of course there are aftermarket ones made that will work as well. If nobody here has one to spare, eBay is probably your next best bet.

Good luck on your search! A PowerBook 145b was one of the first PowerBooks I played with as a kid at someone's house. That lead to me getting a 180 soon after I started collecting Macs. Keep us up to date...hopefully with an adapter it'll fire right up!