340 timing

Well I got my 340 dropped in my 68 dart last night and it runs so thats half the battle. Kickdown doesn't work yet. Still have a header leak just like on the 318 so it must be a warped manifold flange. But, I digress. It has a comp XE268H-10 cam and a Holley 750 dp. What is a good "target" for ignition timing? Is it set with vacuum connected or disconnected? Thanx