That guy at Paramount is pretty helpful with Sun machines- at least was when I called for help on my friend's.
I was thinking you'd just take the distributor over and run it on his machine and get his thoughts on setting it up.
You're right about things changing with longer duration cams. At idle, vacuum is lower than stock. Then coming off idle at light throttle vacuum rises, but hard throttle it of course drops more. So maybe that might have something to do with the issues you've observed?