So just fitted sp1 calipers, with sp1 mc and braided lines, trying to bleed them but having problems...

As if sitting on the bike... The left caliper bleeds through solidly, but can't get the right to bleed properly, using a mityvac and bled it through time and time again but still air coming through...

All the lines and seals seem in good condition so am a bit stumped

Any help much appreciated :)

Have you primed the master cylinder?

Try some ptfe tape around the nipple thread, it could just be air getting in around the thread while it's loose.
Does the level fell normal when you tighten the nipple?.

How do I prime the master? Will try with some ptfe tape too, could be the problem, cheers

I usually put slight pressure on the brake lever, undo the top banjo bolt then pull the lever to the bar, hold it there, then do up the banjo bolt and release the lever. Usually get rid of stubborn air bubbles.