Cannondale Capo chainline

I've recently got a 54cm Capo and am struggling to get a good chainline. The chain stays are quite chunky which is making things a little tricky!
I've a set of Omniums which could use but on offering them up, they look mega tight to the frame so I'm worried about them hitting the stays. I've also tried an older pair of primato cranks with the matching adjustable bb but when I torque them up, the NDS crank touches the frame. Could it be bent?! I then tried a 111mm ISO bb (token) which brought the cranks out but the chain ran rough due to being TOO far out! (Maybe about 8mm crank/stay gap)
I've seen plenty of Capos running both of these set ups, are people using spacers?!
Any advice would be greatly appreciated!

How long are the cranks? Is that frame designed for 165mm cranks only perhaps?

Both sets of cranks are 165mm

You can't adjust Omnium.

How many teeth on your chainring?

Yes, that's right it's not. It's the ends of the cranks that are the issue. It's a 48T chainring. Thanks!

It's the ends of the cranks that are the issue.

Sorry, missed that.

Try the Cannondale thread: considerable expertise there (ie Howard).

I've also tried an older pair of primato cranks ... Could it be bent?!

Very likely.

There's Primatos on all the hire bikes at work and we've had to replace a few cranks/chainsets after (sometimes minor) crashes as the arms have bent and are hitting the stays.

Ok, that makes sense and the NDS arm does look like it curves in very slightly but I wasn't sure, I checked the arm for any damage/dings/scuffs and it's clear. Doesn't explain the Omniums, maybe I'll try fitting them again and tightening them up and then I'll know 100%! Last resort I guess is to buy a new set of Primato cranks!
Thanks...

Weird... got 48t omnium in a 54cm frame installed by Brixton bikes a year or so ago... they did not mention any problems

I have a Capo with 48t Omnium and have no problems, No spacers used