There was an article in the latest edition of the HRCA Collectors magazine on how to convert a HD 8F into a Black5, it was long and detailed and required a great deal of work and skill. The finished article though was very nice ideed.
Thanks to ebay here is a similar conversion but using a Graham Farish Black 5 body. It has a 3 rail Castle chassis with 8F valve gear and an 8F tender with the three rail pick ups. I actually think that it looks slightly better than the conversion using an 8F body as the Farish one has a higher running board.
It runs as well as a inch and a half Castle would which is not amazing power but adequate for 3 or 4 coaches or 10 or so trucks. Better than an 8F which has poor pulling power. Avery nice addition to the loco fleet.
I will copy this to the section on HD based locos.