I think you'd want the largest filters that will fit into
your engine bay. Also, you will want the longest air horns
you can afford, though really all you need is a small one to
get a good effect.

Where are you getting this stuff and what are you paying,
if you don't mind my asking?

Also, I'm really keen on the cold air box that comes stock
on the strombergs. The pancake filters are going to suck in
air that's already been heated by the radiator. Cold air is
more dense and thus has more O2 thus yields better power.

Were I in your position, I'd try to find a KN filter and
air horns that fit the existing intake. If the bolt holes
are different between the stromberg and SU HIF6 intakes,
I know you can use an air intake from a 140 with twin SU HIF6
carbs instead of the stromberg box. I think the more common
solution is to just use a drill to put holes in the right
places, though.

chris