Hi, I used to get ali bellhousings made way back, but stopped when Flowtec started marketing them commercially. I have just reactivated this work in the guise of fitting the Ford type 9 five speed box to the early Kent based engines, particularly the twincam.
As it happens I still have one casting left of the original type (to fit the four speed box) and if you can't find one elsewhere, could possibly get this machined with the new bellhousings, as the real difference is at the rear face with the bolting patterns and I have a jig to drill either.
Let me know if this is any help. It would be a new bellhousing with thread inserts and steel sleeve in the slave cylinder lug. I made and sold about 60 or 70 of the original type. I would need to re-establish a price but I estimate it is likely to be about £200 or so. Can firm this up if you are interested. The Burton version is £365 for comparison.
Paul