Check with victoria british .com . They have some in there not sure what the quality is but they are half the price of motorsports.They do not have them on their web site ,but they do in their catalog. Hope this helps.
If you decide to change engines check with jerry at all z car specialists in fort worth. You should be able to get a decent engine for around 150 or so.If interested send a pm and I will give the details.
I was considering installing SU's on my 76 280 ,but a friend said I may run into trouble. Does anyone know what would be involved in the conversion. Any help would be appreciated.