392 problems

[vbdig]

I have 3 problems I need feedback on, I replaced a 351 crate motor with a 392 crate motor. All of the accesories stayed the same, ( 6al msd, 670 street avenger, etc.) The problems are as follows:
1. Oil pressure is lower than first engine. 4 bar (60psi) at cruise speed, 1 1/2 bar at hot idle. It seems low to me, old engine rarely dropped below 45 psi at idle. Using 20-50 oil, no oil cooler.
2. Bad vibration in shift lever at 4500 rpms and above under hard acceleration. Free reving seems not to be the same, just under hard acceleration.
3. Missing. The engine seems to miss at 3000 rpm. Plugs read good except #7 and #8 which seem to be reading rich. I can hear the right side exhast stutter about that rpm under partial acceleration. I have tried jetting up and down, but problem remains. Now I'm wondering if the hard vibration I feel is a cylinder or two cutting out. This engine has so much more acceleration than the last one I'm not sure if the missing is occuring all of the time and I just can't hear it. If so, what would cause 1 or 2 cylinders to cut out. I did weld on the frame without disconnecting the msd, could I have a problem there?