In my workshop is a BMW 16 valve head and associated fuel injection set up destined for my son in law who is located in Queensland Australia.
This kit is going to be fitted to a 'A' Series engine which is going to be installed in a modified Mini.
Fitting the BMW 8 valve head and BMW 16 valve head both with fuel injection is a well trodden path.
Unless you are going to do a full power conversion I would suggest that fitting a fuel injection system is money not well spent.
Even with my 1380cc full race motor I could not warrant the expense of fitting a fuel injection system and instead fitted two 45DCOE 13 Weber carbs.
Therefore I would suggest that you stick with a normal SU carb and if you want to improve the performance fit a 1 1/2" HS4 SU carb.
Though to get the best performance you do need to carry out other modifications like changing the head and manifolds. The trouble is where do you stop.
https://www.youtube.com/watch?v=fbxEJTTehYg