The quick cure for your oil feed problem is to take the liner out , turn it through 180 degrees and re-insert the liner, then slot and drill the oil hole as low as your crankcase will allow. You will need a rebore, probably.
The slot dimension, for your Comet should be from 5/8ths below the muff to 1 1/32ths below. Drill at the end of the slot at the most acute angle downwards that you can achieve with your drilling facilities
Most racers tend to use larger clearances than road bikes, which is why they do not seize.
As regards two piece head studs-- If the brass insert, inner stud and the outer hollow stud are all scewed
in with sealant there should not be a leak.
Robin.
The slot dimension, for your Comet should be from 5/8ths below the muff to 1 1/32ths below. Drill at the end of the slot at the most acute angle downwards that you can achieve with your drilling facilities
Most racers tend to use larger clearances than road bikes, which is why they do not seize.
As regards two piece head studs-- If the brass insert, inner stud and the outer hollow stud are all scewed
in with sealant there should not be a leak.
Robin.