I've seen a set of "Crocker" style cycle tail lights on a roadster. They are repopped and available. Looked good too... Just did a google search and they come in a range of $$$$.
Bit of an old thread but i was going to run '32 lights on a '32 pickup bracket that i have, but because i only had one bracket and one light.. and we need a pair over here.. i was going to source another, until i found an original set of '39 lights.. which is pretty rare in Australia. So i've gone that route for now..
Im using 38 Chrysler Airflow taillights on mine, reasonably hard to come by and pretty ****** expensive but the are killer looking. As for some pretty cool English taillights heres a few. http://www.s-v-c.co.uk/product/l539-lucas-stop---tail--pair-/