73 up slant six to SB conversion kit

Hey! A week ago i got a 74 duster which came with a 360/727. The car already had 360 decals on it and the seller told me everything would be alright. Now i learned that not only the engine is a POS but the k member is also a slant six one. Here in gernany its hard to find a proper k member, thats why i hope to find at least a conversion kit by Schumacher eg here, although they seem to be not in stock everywhere.
Thanks in advance and looking forward to replies.