You can add a hydraulic cam with specifications to match the old factory 30/30 with factory Z/28 valve springs added to your heads (after they are pinned to keep the rocker studs from pulling out).
Power Packs were introduced in 1956 as the first modification to the original SBC head and didn't change since they were introduced. They were designed for a 265 V-8 not the monstrously large 283. The 283 did use fuelie heads back in 1964 (of which there are seven different castings changing the chamber, ports and spark plug location, and later adding front bolt holes for accessory mounting in 1968 even though they were not used until 1969). That would be my choice for a stock head.
Aside from the bolt holes a set of Fuelie heads would do more to pump up your ride than any Power Pack head could (and I personally think Fuelie heads are junk when compared to the much more computer designed Vortec pick-up truck head introduced in 1996). They can still be found, but like anything this old, the head will need a lot of machine work to make them new again (new guides, new valve seats, spring pockets machined, machined for screw in studs, and decking if at all possible as a lot of them were angle cut far, far too much over time; and are paper thin now which makes them subject to warping). You can buy new cast iron aftermarket heads disguised to look like old Chevy heads (they mill on the distinctive camel humps with a CNC mill) and they are not much more expensive in price than that required to remanufacture your Power Pack heads to make them seal and work with unleaded gasoline.
I would bolt on a set of 305 heads as is (maybe change the springs if you are going to put a cam in her) as they are the right size for a 283 (you do not need any head with intake ports over 160 cc in size with a 283 maybe a 170 cc if you wanted to race her on weekends and for comparison early Fuelie heads were only 150 cc).