Rufus
Running pretty much the same setup as you. See my profile.
Guess the easiest way is to say check out the engine photos on my gallery but I 'll try to explain - see page three (3) on the gallery photos.
I also used the drop filter base. I trimmed and used gaskets to keep a seal. I then used a K+N filter and a K + N filter top. The two combined give more than enough air flow.
I trimmed/hacksawed all of the top off the carby down flush with the float bowls. The top K + N filter now sits about 1" above the carby. The ring/circular K + N filter runs around at the same level as the bowls due to the drop base plate.
Put a drop base on. Place a torch inside and close the hood/bonnet and you can see how much space you have above the carby to play with.
You may not need to be as radical as I have been, or you may be able to use a higher ring/circular K + N filter.
Trial and error.
Cheers
Bernie