750 Sport not quite running right HELP !!!!

[Gum]

Ok, quick run down, new engine and I start it up. Not quite right, the front cyl is not firing well and even worse at idle, I cant get it running under a few thousand RPM. Pull the plugs, front one wet, comp test perfect, and it has spark. Ok, ive put the carbs on back to front. My excuse is I didnt pull them off. [ Yes im stupid ] So now im happy as I have found the problem. Swap carbs, run it, still the same. Ok, the Tacho does not work and its wired up to the coil on the front cyl, so I remove this and at the same time swap the HT leads and the wires from the Dyna Ign. So now if its the coil the rear will be the dead or at least tired cyl. Start her up and shes all good. But im still having unstable idle, I set her up at what I think is still a little high at idle [ if I remember back 30 years they just thumped over and very stable ] and then she just stalls. I went through both carbs a year ago so they should be ok. I dont like the rubbers on the inlet manifolds to heads, they seem very soft and distort when tightened, [ maybe a vacuum leak ??? ]. Or the coils ??? but at low rpm I would think that the coils should be fine as at high rpm it runs well. One thing is I think that the Tacho wire did cause some issues, tomorrow I will swap the coils back with out the tacho wire and check, just to later here to run it. Any help would be great.

Thanks Gum