street and strip gears (have a store on ebay) do a heavy duty bw 78 centre. i've used 2 second hand commo ones and they shat themselfs with a bit of circle work etc. its $650 and can be shimmed up as much as u like. c/w and pinion can be found in the ratio you are after from all the above mentioned cars
yea its all sorted now. managed to cut and shut a sedan roof onto it. it will probly never be the same but it turned out pretty good considering i'm not a panel beater and i've never done a roof chop before