ive had a prick of a time getting the right uni filter, but...measure the outer diameter of your carb... probably 38mm or 44mm...seem to be the most common. i find with unifilters they just slide off as you tighten the clamp, they got no groove inside to hold em on.... or the clamps too wide
im using a 35mm, and ended up using tie wire. lets it grip on to the groove thats on your carb.
angle or straight is a matter of taste and space really.