Classic/Antique Car Repair: 51 Pontiac 8, 12 volt, straight 8

Question
Hi there, I have a problem with my flathead straight 8. It has recently been converted to 12v.
1): it is breathing quite heavy from both road breather and oil filler...mainly on idle.
2): when started it appears to be burning the points quite quickly and in 1 instance actually made the coil explode.
3): It will start and tick over...although a little lumpy...but will not rev properly at all...like it cannot find all the cylinders.
4): Was running perfect when it went into the paint shop a year ago and has stood since but now having these problems.

Please please please can you help.

Answer
I am not a fan of converting to 12 volt and if not done correctly can cause these problems. The puffing sounds like the rings have stuck and the engine should have a compression test to determine the condition of the engine before anything is done.
Brad