Only one note here. To get 450 "real" hp from the 390, it will take a cam, carb and compression combination that will make the car decidedly unpleasant on the street.
With the mild specs I'm seeing here, I would suggest figuring 350-375 is more like it. That's still a lot of power in a 2200# car.
Oil pans? Look into Aviaid. They make a 9 qt "t" style FE pan designed for a Cobra. They made the same pan for original Cobras. I used one on my 427SO. See pics in my gallery.
My SO made just over 480hp on the dyno with 11:1 comp, 916cfm Holley (Carb Shop), Shelby Sidewinder and .560/580 lift cam on 108 degree lobe centers, Dove MR heads with TP sized valves and Dove roller rockers. Granted that number was through mufflers, but still, 450 from a 390 is reaching a bit, unless it is a drag race piece.
Yes, to use hyd lifter block with solids, the lifter gallery
oil supply must be cut off. With my engine, my builder recommended restricting
oil to the rockers, which we did and I experienced no problems.
BTW, if that 69 block is the ribbed variety, it might take an overbore out to 406 cid. Have it sonic tested for core shift first.
Al